Mirror reflective element assembly

ABSTRACT

A mirror assembly for a vehicle includes a mirror element having at least one substrate that has a forward surface and a rearward surface. The mirror element comprises at least one substantially reflective metallic layer sandwiched between a respective pair of substantially transparent non-metallic layers. Each of the substantially transparent non-metallic layers and the substantially reflective metallic layer have a selected refractive index and a selected physical thickness such that the reflective element is selectively spectrally tuned to substantially transmit at least one preselected spectral band of radiant energy therethrough while substantially reflecting other radiant energy. A radiant energy emitting element is disposed at or near the rearward surface of the at least one substrate. The radiant energy emitting element is configured to emit radiant energy with a peak intensity within the at least one preselected spectral band.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a 371 application of PCT Application No.PCT/US2003/029776, filed Sep. 19, 2003, which claims priority of U.S.provisional applications, Ser. No. 60/412,275, filed Sep. 20, 2002 byMcCabe for ELECTROCHROMIC MIRROR ASSEMBLY; Ser. No. 60/424,116, filedNov. 5, 2002 by McCabe for ELECTROCHROMIC MIRROR ASSEMBLY; and Ser. No.60/489,816, filed Jul. 24, 2003 by McCabe for ELECTROCHROMIC MIRRORASSEMBLY, which are all hereby incorporated herein by reference in theirentireties.

FIELD OF THE INVENTION

The present invention relates to a mirror reflective element assemblyfor a vehicle, such as an electro-optic mirror reflective elementassembly, such as an electrochromic interior or exterior rearview mirrorreflective element assembly, and, more particularly, to a rearviewmirror reflective element assembly which provides transmission ofdisplay information or illumination or radiant energy through thereflective element of the mirror reflective element assembly, whileproviding sufficient reflectance of the reflective element. Aspects ofthe present invention are equally applicable to interior and exteriormirror reflective element assemblies, as well as to prismatic mirrorreflective element assemblies or other mirror reflective elementassemblies having a single glass substrate.

BACKGROUND OF THE INVENTION

Variable reflectivity mirror assemblies, such as electrochromic mirrorassemblies are known and are widely implemented in vehicles. Thereflective element of the mirror assemblies often include two substratesor glass elements. The back or outer surface of the second substrate(commonly referred to as the “fourth surface” of the reflective element)may include a silvered coating to provide reflectance of an image. Inembodiments where the mirror assembly may include a display, a windowmay be formed, such as by sand blasting, laser etching or the like,through the silvered coating, such that display information may betransmitted through the window for viewing by the driver. The windowprovides a highly transmissive, generally spectrally neutral window forthe display. However, the window defines an area of the reflectiveelement that no longer has the reflective coating, such thatreflectivity is lost in the window area. Therefore, the size and thequantity of displays that can be provided at the mirror reflectiveelement is limited.

It is known to provide a metallic reflective layer on an inward surfaceof the second substrate of the electrochromic reflective element(commonly known in the art as a “third surface” of the reflectiveelement), such as disclosed in U.S. Pat. No. 3,280,701, which is herebyincorporated herein by reference. An electrochromic medium may bepositioned between the metallic layer and a transparent electricallyconductive layer on the inward surface of the first substrate (i.e., the“second surface” of the reflective element). However, there are concernswith the electrochromic medium of such mirror assemblies contacting themetallic layer, since chemical and/or electro-chemical attack on themetallic layer may result in corrosion of the metallic layer.

As disclosed in U.S. Pat. No. 5,724,187, which is hereby incorporatedherein by reference, a metallic conductive layer may be disposed on thethird surface, with a protective layer, such as a transparentsemi-conductive layer of indium tin oxide, disposed on the metalliclayer. The electrochromic medium is then positioned between theprotective layer and a conductive layer on the inward surface of thefirst substrate. It is preferable for such designs to include anadhesion layer, such as a second transparent semi-conductive layer, suchas indium tin oxide, or another metallic layer, between the metalliclayer and the inward surface of the second substrate, in order toenhance adhesion of the metallic layer to the second substrate.

In electrochromic mirror assemblies which include a display that maytransmit through the substrates of the reflective element, the metalliclayer or coating must be thin enough to be transmissive to allow viewingof the display through the metallic coating. It is known to provide athinner metallic coating in a display area to provide increasedtransmissivity (but with a consequently reduced reflectivity) only inthe display area or areas of the reflective element, such as disclosedin U.S. Pat. No. 6,356,376, which is hereby incorporated herein byreference. However, such designs have layers or coatings that arerelatively thin (often less than 150 Å or thereabouts in thickness) andso any variation in metallic layer thickness may lead to a significantvariation in light transmission through such thin metallic coatings.Thus, such significantly thin metallic coatings or layers may have asubstantially low variability tolerance for the thickness and mayrequire a substantially uniform thickness coating, in order to providethe desired results. Such tolerances and uniformity may be difficult toachieve through sputter coating or other coating processes typicallyused in the manufacture of such reflective elements. Therefore, suchsignificantly thin metallic coatings may be difficult and costly tomanufacture.

An example of a known electrochromic reflective element is shown inFIG. 1. The reflective element includes an electrochromic (EC) mediumlayer and a metallic reflective layer sandwiched between conductivelayers at the front and rear glass substrates. A display is positionedat a rear surface of the rear substrate (the fourth surface of thereflective element). The display emits light through the substrates andlayers therebetween so as to be viewable by a person viewing the firstsurface of the reflective element. Such known reflective elementsprovide little or no spectrally selective transmission characteristicsof visible light, as can be seen with reference to FIG. 1A (which showsthe transmissivity of the ITO and silver layers at the rear substrateversus the wavelength of the radiant energy), and may be subject tochemical/electrochemical corrosion through contact with the EC medium.

Sometimes it is desired to have an illumination source and/or a cameraor imaging device or sensor at an interior rearview mirror assembly forilluminating and/or capturing images of the interior cabin of thevehicle, such as part of a cabin monitoring system, a driveralertness/drowsiness detection system, an intrusion detection system, aseat occupancy detection system and/or the like. The illuminationsources and imaging device, if provided at the interior rearview mirrorassembly, are typically positioned around the bezel, chin or eyebrowportion of the mirror casing or at a pod or module associated with themirror assembly or elsewhere in the vehicle. The illumination sourcesand imaging device cannot typically be positioned within the mirrorcasing due to the difficulties encountered in projecting light orillumination through the reflective element to the cabin and allowinglight from within the cabin to pass through the reflective element tothe imaging device. Typically, such transmissivity of light, even ofinfrared or near infrared light, through the reflective element may notbe achieved utilizing reflective coatings that comprise a metalliclayer, such as a thin silver or silver alloy or aluminum or aluminumalloy layer or the like. In such applications, the infrared or nearinfrared light emitted by the illumination source may reflect back intothe cavity of the mirror casing, such that a desired amount of light maynot reach the cabin and such that the imaging device may be adverselyaffected by the reflectant light.

Therefore, there is a need in the art for an electrochromic mirrorassembly which provides sufficient reflectivity and sufficienttransmissivity to allow for transmission of display information orillumination through the reflective element, and which overcomes theabove disadvantages and shortcomings of the prior art.

SUMMARY OF THE INVENTION

The present invention provides an interior or exterior rearview mirrorassembly that has a mirror reflective element that may be spectrallytuned to substantially transmit light having a particular wavelength orrange of wavelengths, while substantially reflecting other light. Themirror reflective element may comprise a third surface reflectiveelement having a particular combination or stack of at least partiallyconductive layers (such as semi-conductive layers formed of at leastpartially conducting inorganic oxides, such as doped or undoped indiumoxide, doped or undoped tin oxide, doped or undoped zinc oxide, doped orundoped nickel oxide, and/or doped or undoped tungsten oxide or thelike) and metallic layer(s) at the third surface. The mirror assembly issuitable for including a display element which emits and transmitsviewable information through the reflective element of the mirrorassembly. More particularly, the mirror assembly of the presentinvention is suitable for including a display on demand (DOD) type ofdisplay. The mirror assembly of the present invention provides aparticular combination of reflector design or designs suitable for adisplay on demand type of display which are economical and which matchand/or make most beneficial use of a particular light emitting displayelement and color thereof. The present invention thus provides aspectrally selective transmission of visible light characteristic to thereflective element of the mirror assembly, while maintaining asubstantially non-spectrally selective, substantially untintedreflectant characteristic, and while maintaining a relatively highphotopic reflectance, such as greater than approximately 60% photopicreflectivity, more preferably greater than approximately 70% photopicreflectivity, and most preferably greater than approximately 80%photopic reflectivity. The spectrally selective transmissivity of thereflective element may thus be selected or tuned to optimizetransmission of a particular spectral band or range of light wavelengthsat least primarily emitted by the display element.

According to an aspect of the present invention, a mirror assembly for avehicle comprises a mirror element including at least one substratehaving a forward surface facing towards a viewer of the mirror assemblyand a rearward surface facing away from a viewer of the mirror assembly.The mirror element comprises at least one substantially reflectivemetallic layer sandwiched between a respective pair of substantiallytransparent non-metallic layers. Each of the substantially transparentnon-metallic layers and the substantially reflective metallic layer havea selected refractive index and a selected physical thickness such thatthe reflective element is selectively spectrally tuned to substantiallytransmit at least one preselected spectral band of radiant energytherethrough while substantially reflecting other radiant energy. Aradiant energy emitting element is disposed at or near the rearwardsurface of the at least one substrate. The radiant energy emittingelement is operable to emit radiant energy towards the rearward surfaceand through the mirror element. The radiant energy emitting element isoperable to emit radiant energy with a peak intensity within the atleast one preselected spectral band.

Optionally, the at least one preselected spectral band may comprise apreselected band of visible light, while the radiant energy emittingelement may be operable to emit visible radiant energy or light with apeak intensity within the preselected spectral band of visible light.The radiant energy emitting element thus may provide a display on demandtype of display for viewing of displayed or emitted information throughthe reflective element.

Optionally, the at least one preselected spectral band may comprisefirst and second preselected bands of radiant energy, while the radiantenergy emitting element comprises first and second radiant energyemitting elements. The first radiant energy emitting element may beoperable to emit radiant energy with a peak intensity within the firstpreselected spectral band of radiant energy and the second radiantenergy emitting element may be operable to emit visible radiant energywith a peak intensity within the second preselected spectral band ofradiant energy.

Optionally, the at least one preselected spectral band may comprise apreselected band of near infrared radiant energy, while the radiantenergy emitting element may be operable to emit near infrared radiantenergy with a peak intensity within the preselected spectral band ofnear infrared radiant energy. The mirror assembly may include an imagingsensor at or near the rear surface that may be sensitive to nearinfrared radiant energy.

Optionally, the mirror reflective element may comprise an electro-opticor electrochromic mirror element, and may comprise an electrochromicmedium sandwiched between a pair of substrates. The non-metallic andmetallic layers may be disposed on a third surface (the surface of therear substrate that opposes electrochromic medium and the frontsubstrate).

Optionally, the mirror reflective element may comprise a prismaticmirror element. The alternating non-metallic and metallic layers may bedisposed on a rear surface of the prismatic element or substrate. Theradiant energy emitting element may be positioned at a rear layer of thealternating layers and operable to emit radiant energy or light throughthe layers and the prismatic substrate, such that the informationdisplayed or emitted by the radiant energy emitting element is viewablethrough the prismatic reflective element by a driver or occupant of thevehicle, while the prismatic reflective element substantially reflectslight having other wavelengths or spectral bands. The radiant energyemitting element thus may provide a display on demand type of display tothe prismatic mirror element.

According to another aspect of the present invention, an electrochromicmirror assembly for a vehicle comprises an electrochromic mirror elementcomprising a first substrate having first and second surfaces and asecond substrate having third and fourth surfaces. The first and secondsubstrates are arranged so that the second surface opposes the thirdsurface with an electrochromic medium disposed therebetween. The thirdsurface of the second substrate comprises a transflective reflectorcomprising a first substantially transparent semi-conductivenon-metallic layer contacting the electrochromic medium, a secondsubstantially transparent semi-conductive non-metallic layer, and asubstantially reflective metallic conductive layer sandwiched between(and electrically in contact/connection with) the first and secondsubstantially transparent semi-conductive non-metallic layers. When themirror element is viewed from outside the first surface (such as by adriver or passenger within the vehicle), the mirror element issubstantially spectrally untinted (i.e., is substantially spectrallyunselective in photopic reflectivity) when no voltage is applied acrossthe electrochromic medium. The mirror element is at least partiallyspectrally selective in transmission (i.e., is at least partially tintedfor transmittant light) and exhibits a spectrally selective transmissioncharacteristic, which is established by the refractive indices andphysical thicknesses of the first and second substantially transparentsemi-conductive non-metallic layers and the substantially reflectivemetallic conductive layer. The mirror assembly includes a light emittingor display element disposed at the fourth surface of the secondsubstrate which is operable to emit light having an emitted spectralcharacteristic through the mirror element. The transflective reflectoris configured to exhibit a spectrally selective transmissioncharacteristic so as to substantially transmit light having a spectralband in regions at or near the emitted spectral characteristic and tosubstantially reflect other light.

Optionally, the second substantially transparent semi-conductivenon-metallic layer may contact the third surface of the secondsubstrate. Optionally, the transflective reflector may comprise two ormore substantially reflective metallic conductive layers. Each of thetwo or more substantially reflective metallic conductive layers may besandwiched between a respective pair of substantially transparentsemi-conductive non-metallic layers disposed between the electrochromicmedium and the second substrate.

Optionally, the transflective reflector may substantially transmit lightor radiant energy having a spectral band in the near infrared region ofthe spectrum, while the light emitting or display element may emit nearinfrared light or radiant energy through the transflective reflector.The mirror assembly may include an imaging sensor at the fourth surfacethat is operable to sense near infrared light.

Optionally, the transflective reflector may substantially transmit lighthaving a first spectral band at a first visible region of the spectrum,and may also substantially transmit light having a second spectral bandat a second visible region of the spectrum. The light emitting ordisplay element may emit light that has a peak intensity at or near thefirst visible region, while the mirror assembly may include a secondlight emitting element at the fourth surface that may emit light thathas a peak intensity at or near the second visible region.

According to another aspect of the present invention, an electro-opticmirror assembly, such as an electrochromic mirror assembly, for avehicle comprises an electrochromic mirror element comprising a firstsubstrate having first and second surfaces and a second substrate havingthird and fourth surfaces. The first and second substrates are arrangedso that the second surface opposes the third surface, with anelectrochromic medium disposed between the second substrate and thefirst substrate. The mirror element comprises a transflective reflectorat the third surface, which comprises at least one conductive metallicreflective layer sandwiched between first and second substantiallytransparent semi-conductive non-metallic layers. The first substantiallytransparent semi-conductive non-metallic layer contacts theelectrochromic medium. The mirror assembly includes a display element atthe fourth surface of the second substrate. A refractive index and aphysical thickness of each of the first and second substantiallytransparent semi-conductive non-metallic layers and the substantiallyreflective metallic conductive layer are selected such that thetransflective reflector is selectively spectrally tuned to substantiallytransmit at least one preselected spectral band of visible lighttherethrough while substantially reflecting other visible light. Thedisplay element is configured to emit visible light with a peakintensity within the preselected spectral band.

According to another aspect of the present invention, a mirror assemblyfor a vehicle includes a mirror element and a radiant energy emittingelement. The mirror element includes a substrate having a forwardsurface facing towards a viewer of the mirror assembly and a rearwardsurface facing away from a viewer of the mirror assembly. The mirrorelement includes at least one substantially reflective metallic layersandwiched between a respective pair of substantially transparentnon-metallic layers disposed at the rearward surface of the substrate.Each of the substantially transparent non-metallic layers and thesubstantially reflective metallic layer having a selected refractiveindex and a selected physical thickness such that the mirror element isselectively spectrally tuned to substantially transmit at least onepreselected spectral band of radiant energy therethrough whilesubstantially reflecting other radiant energy. The radiant energyemitting element is operable to emit radiant energy towards the rearwardsurface and through the mirror element. The radiant energy emittingelement is operable to emit radiant energy with a peak intensity withinthe at least one preselected spectral band.

The substrate may comprises a single substrate. The single substrate maycomprise a prismatic or wedge-shaped substrate. The radiant energyemitting element and alternating layers thus may provide for a displayon demand type of display for a prismatic (or flat or curved) mirrorassembly.

According to other aspects of the present invention, an electrochromicmirror assembly for a vehicle includes an electrically variable mirrorelement. The mirror element includes a first substrate having first andsecond surfaces and a second substrate having third and fourth surfaces.The first and second substrates are arranged so that the second surfaceopposes the third surface. The second substrate includes a conductivestack on the third surface. The conductive stack may comprise a firstelectrically conductive or semi-conductive layer deposited on the thirdsurface, a reflective or metallic layer of reflective or metallicmaterial on the first electrically semi-conductive layer, and a secondelectrically conductive or semi-conductive layer on the reflectivelayer. The mirror element includes an electrochromic medium disposedbetween the second electrically semi-conductive layer of the secondsubstrate and the electrically semi-conductive coating on the secondsurface of the first substrate. The thicknesses and materials of thelayers are selected to provide or exhibit a spectrally selective visiblelight transmission characteristic for a particular spectral band orrange of wavelengths to provide enhanced transmissivity of the spectralband of light through the reflective element while providing sufficientreflectivity of other light.

In one form, the electrochromic mirror assembly may include a displayelement positioned at the fourth surface, wherein the display element isoperable to emit light through the mirror element for viewing by adriver of the vehicle. The thicknesses of the particular layers of theconductive stack are selected such that the mirror element is spectrallytuned to transmit a predetermined spectral band of light therethrough.The spectral band that is transmittable through the mirror element maybe selected to match a spectral band or range of light wavelengthsemitted by the display element, such that the mirror element isspectrally tuned for the particular display element positioned at thefourth surface of the mirror element. The mirror element thus may bespectrally tuned to match at least a portion of the transmissive band orrange of wavelengths of the mirror element to a particular band or rangeof wavelengths of the light being emitted by the display element. In oneform, the peak transmissivity of the transmissive band of the mirrorelement is selected to match the peak intensity of the spectral bandemitted by the display element. The conductive stack preferably providesat least approximately 60 percent photopic reflectance (preferably asmeasured in accordance with Society of Automotive Engineers testprocedure SAE J964a, which is hereby incorporated herein by reference inits entirety), more preferably at least approximately 70 percentphotopic reflectance, and most preferably at least approximately 80percent photopic reflectance, while providing at least approximately 10percent transmission, preferably at least approximately 15 percenttransmission, more preferably at least approximately 20 percenttransmission, and most preferably at least approximately 30 percenttransmission, of at least a particular spectral band of light.Preferably, the physical thicknesses of the layers are selected to limittinting and/or color interference affects as seen in the mirror element(i.e. to provide a neutral reflector) and to spectrally tune the mirrorelement for a transmission characteristic for providing enhancedtransmissivity through the mirror element for a particular spectral bandor range of wavelengths, in order to match the transmissivity of themirror element to the spectral band of emission of light from thedisplay element.

The semi-conductive layers and metallic layer of the conductive stackmay be deposited at the third surface via a sputter coating process. Thepresent invention thus may provide a low cost reflective element whichprovides for sufficient transmission of a particular spectral band orbands of visible light and sufficient reflectance at the third surfaceof the mirror assembly (with at least 60% photopic reflectancepreferred, more preferably, with at least 70% photopic reflectance, andmost preferably, with at least 75% photopic reflectance). Preferably,the semi-conductive layers, such as indium tin oxide or the like,sandwiching the metallic layer are formed of the same material. Thus,for example, a conductive stack of alternating layers may comprise ametallic layer of silver sandwiched between two semi-conductive layersof indium tin oxide.

According to another aspect of the present invention, an electro-opticor electrochromic interior rearview mirror assembly comprises anelectro-optic or electrochromic mirror reflective element. Theelectro-optic mirror element provides a substantially reflective mirrorelement having a first region having a first reflectivity and a firsttransmissivity and a second region having a second reflectivity and asecond transmissivity. The electro-optic mirror element includes adisplay element positioned at or behind the second region and operableto transmit light through the second region. The first reflectivity isgreater than the second reflectivity. Preferably, the second regionprovides at least approximately 25% transmissivity of light from thedisplay.

Therefore, the present invention provides a mirror reflective element,such as a third surface reflective element or mirror element or a fourthsurface reflective element or a prismatic reflective element or thelike, which is sufficiently and spectrally selectively transmissive orspectrally tuned to allow a particular spectral range or band of lightto pass therethrough from a display at the rear surface of the mirrorreflective element. The layers of the reflective element are selected orspectrally tuned to match one or more predetermined or selected spectralbands or ranges of wavelengths and to thus pass the predeterminedspectral bands of light therethrough, while being substantiallyreflective to other spectral bands or wavelengths of light, and do notrequire windows or apertures formed in the reflective metallic layer ofthe reflective element.

These and other objects, advantages, purposes, and features of thepresent invention will become more apparent from the study of thefollowing description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a conventional electrochromic mirrorreflective element;

FIG. 1A is a graphical depiction of the transmissivity of visible lightof the conventional electrochromic mirror reflective element of FIG. 1;

FIG. 2 is a perspective view of an interior rearview mirror assembly inaccordance with the present invention;

FIG. 3 is a sectional view of the mirror assembly taken along the lineIII-III in FIG. 2;

FIG. 4 is a sectional view of a second substrate and opaque conductiveand reflective layers suitable for use in the mirror assembly of FIG. 2;

FIG. 5 is a front elevation of a second substrate of a reflectiveelement in accordance with the present invention, with a tab-out portionto facilitate electrical connection with the conductive layers;

FIG. 6 is a sectional view of the second substrate taken along the lineVI-VI in FIG. 5;

FIG. 7 is a perspective view of another interior rearview mirrorassembly in accordance with the present invention, with a display;

FIG. 8 is a sectional view of a reflective element of the mirrorassembly taken along the line VIII-VIII in FIG. 7;

FIG. 9 is a sectional view similar to FIG. 6 of a second substrate inaccordance with the present invention, which is suitable for use in themirror assembly of FIG. 7, and includes a tab-out portion to facilitateelectrical connection with the conductive layers;

FIG. 10 is a sectional view of another second substrate and transmissiveconductive and reflective layer or stack in accordance with the presentinvention suitable for use in a mirror assembly having a display;

FIG. 11 is another sectional view of a particular embodiment of areflective element of the present invention;

FIG. 11A is a graphical depiction of the transmissivity of thereflective element of FIG. 11;

FIG. 11B is a graphical depiction of the emission spectrum of thedisplay element for the reflective element of FIG. 11;

FIG. 12 is a sectional view of another particular embodiment of areflective element of the present invention;

FIG. 12A is a graphical depiction of the transmissivity of thereflective element of FIG. 12;

FIG. 12B is a graphical depiction of the emission spectrum of thedisplay element for the reflective element of FIG. 12;

FIG. 13 is a sectional view of another particular embodiment of areflective element of the present invention;

FIG. 13A is a graphical depiction of the transmissivity of thereflective element of FIG. 13;

FIG. 14 a sectional view of a particular embodiment of a double stackreflective element of the present invention;

FIG. 14A is a graphical depiction of the transmissivity of the doublestack reflective element of FIG. 14;

FIG. 14B is a graphical depiction of the emission spectrum of thedisplay element for the double stack reflective element of FIG. 14;

FIG. 15 a sectional view of another particular embodiment of a doublestack reflective element of the present invention;

FIG. 15A is a graphical depiction of the transmissivity of the doublestack reflective element of FIG. 15;

FIG. 16 a sectional view of a particular embodiment of a multiple stackreflective element of the present invention;

FIG. 16A is a graphical depiction of the transmissivity of the multiplestack reflective element of FIG. 16;

FIG. 17 a sectional view of another particular embodiment of a multiplestack reflective element of the present invention;

FIG. 17A is a graphical depiction of the transmissivity of the multiplestack reflective element of FIG. 17;

FIG. 18 is a forward facing view of another electro-optic mirrorreflective element in accordance with of the present invention;

FIG. 19 is a sectional view of another reflective element in accordancewith the present invention, which is capable of transmitting nearinfrared illumination therethrough;

FIG. 20 is a sectional view of another reflective element in accordancewith the present invention;

FIG. 21 is a sectional view of another reflective element in accordancewith the present invention;

FIG. 22 is a graphical depiction of the transmissivity of light throughthe cover and rear substrate of the reflective elements of FIGS. 19-21;

FIG. 23 is a sectional view of another reflective element in accordancewith the present invention, which is capable of transmitting nearinfrared illumination therethrough;

FIG. 24 is a sectional view of another reflective element in accordancewith the present invention;

FIG. 25 is a sectional view of another reflective element in accordancewith the present invention;

FIG. 26 is a graphical depiction of the transmissivity of light throughthe rear substrate and IRT stack of the reflective elements of FIGS.23-25;

FIG. 27 is a graphical depiction of the transmissivity of light throughthe front substrate and enhanced semi-conductive layers of thereflective element of FIG. 24;

FIG. 28 is a graphical depiction of the transmissivity of light throughthe front substrate and enhanced semi-conductive layers of thereflective element of FIG. 25;

FIG. 29 is a sectional view of a reflective element similar to thereflective element of FIG. 25, with an anti-reflective stack or layerson a rear surface of the rear substrate in accordance with the presentinvention;

FIG. 30 is a sectional view of another reflective element in accordancewith the present invention; and

FIG. 31 is a graphical depiction of the transmissivity of light throughthe rear substrate and IRT-DOD stack of the reflective element of FIG.30; and

FIG. 32 is a sectional view of a prismatic reflective element inaccordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings and the illustrative embodiments depictedtherein, an electrochromic interior rearview mirror assembly 10 ismounted to a mounting button 12 mounted at an interior surface of awindshield 14 of a vehicle (FIG. 2). Mirror assembly 10 includes ahousing or casing 15 and an electrochromic reflective element or mirrorelement or cell 16 which has electrically variable reflectivity.Reflective element 16 includes first and second glass substrates 22, 24,and provides a third surface reflective element, whereby the reflectivecoating of the reflective element 16 is deposited on the third surface24 a of the substrates (FIG. 3). An electrochromic medium 40 and aplurality of metallic and non-metallic conductive or semi-conductivelayers 28 are disposed between the electrochromic medium 40 and thesecond substrate 24. The refractive indices and physical thicknesses ofthe layers are selected to maximize transmission of a particularspectral band of light while substantially reflecting other light toprovide a desired degree of photopic reflectance, while also providingthe desired degree of conductivity across the layers.

Although shown and described herein as being implemented in an interiorrearview mirror assembly of a vehicle, the reflective element or mirrorelement of the present invention is equally suitable for or applicableto other electro-optic reflective elements, or reflective elements forexterior rearview mirror assemblies for vehicles or for other mirrorassemblies, without affecting the scope of the present invention. Also,although shown and described as an electrochromic reflective element,aspects of the present invention may be equally applicable to prismaticreflective elements (such as described below with respect to FIG. 32) orto exterior reflective elements, without affecting the scope of thepresent invention. Also, the mirror element of the present invention maycomprise a substantially flat element or substrate or may comprise acurved element or substrate, such as a convex element or asphericelement or the like, without affecting the scope of the presentinvention.

Electrochromic reflective element 16 comprises a first or frontsubstantially transparent substrate 22 and a second or rearsubstantially transparent substrate 24 (which may be glass substrates orthe like). The first substrate 22 includes an electrically conductive orsemi-conductive layer 26, such as a tin oxide (doped or undoped) orindium tin oxide (ITO) or any other transparent electricallysemi-conductive layer or coating or the like (such as indium ceriumoxide (ICO), indium tungsten oxide (IWO), or indium oxide (IO) layers orthe like or a zinc oxide layer or coating, or a zinc oxide coating orthe like doped with aluminum or other metallic materials, such as silveror gold or the like, or other oxides doped with a suitable metallicmaterial or the like), deposited on an inward surface 22 a of firstsubstrate 22 (i.e., the second surface 22 a of the reflective element16).

Also, the first (or forward or outermost) surface 22 b of frontsubstrate 22 (exposed to the atmosphere exterior of the mirror assembly)may be optionally coated with an anti-wetting property such as via ahydrophilic coating (or stack of coatings), such as is disclosed in U.S.Pat. Nos. 6,193,378; 5,854,708; 6,071,606; and 6,013,372, the entiredisclosures of which are hereby incorporated by reference herein. Also,or otherwise, the first (outermost) surface 22 b of front substrate 22may be optionally coated with an anti-wetting property such as via ahydrophobic coating (or stack of coatings), such as is disclosed in U.S.Pat. No. 5,724,187, the entire disclosure of which is herebyincorporated by reference herein. Such hydrophobic property on thefirst/outermost surface of electrochromic mirror reflective elements(and on the first/outermost surface of non-electrochromic mirror,non-electro-optical conventional reflective elements) can be achieved bya variety of means, such as by use of organic and inorganic coatingsutilizing a silicone moeity (for example, a urethane incorporatingsilicone moeities) or by utilizing diamond-like carbon coatings. Forexample, long-term stable water-repellent and oil-repellentultra-hydrophobic coatings, such as described in PCT Application Nos.WO0192179 and WO0162682, the entire disclosures of which are herebyincorporated by reference herein, can be disposed on the first(outermost) surface 22 b of front substrate 22. Such ultra-hydrophobiclayers comprise a nano structured surface covered with a hydrophobicagent which is supplied by an underlying replenishment layer (such as isdescribed in Classen et al., “Towards a True ‘Non-Clean’ Property:Highly Durable Ultra-Hydrophobic Coating for Optical Applications”, ECC2002 “Smart Coatings” Proceedings, 2002, 181-190, the entire disclosureof which is hereby incorporated by reference herein).

Second or rear substrate 24 includes at least three layers or coatingsdefining a reflective and conductive layer or stack or ISI layer orstack 28 (i.e., the combination or stack of a layer of: asemi-conducting coating, such as an ITO layer or the like; a metalliclayer, such as a layer of silver, aluminum or an alloy of silver or analloy of aluminum or other metal or metal alloy; and another layer of asemi-conducting coating, such as an ITO layer or the like, as discussedbelow, is referred to herein as an ISI stack or layer) on an inwardsurface 24 a of second substrate 24 (or the third surface of thereflective element). Thus, an ISI stack 28 comprises a metallic layersandwiched between two semi-conducting layers (both of which preferablyare the same material, but either of which can be different from theother). In the illustrated embodiment of FIG. 4, ISI layer 28 comprisesa first semi-conductive layer 30 disposed on inward surface 24 a ofsecond substrate 24, a second semi-conductive layer or adhesion layer 32disposed on semi-conductive layer 30, a metallic layer or coating 34disposed on semi-conductive layer 32, and a transparent semi-conductivelayer or passivation layer 36 disposed on metallic layer 34. As shown inFIGS. 3 and 4, first semi-conductive layer 30 extends outwardly from theother ISI layers 32, 34 and 36, in order to provide for electricalconnection with bus bars 38 of mirror assembly 10. Although referred toherein as an “ISI layer” or an “ISI stack”, the conductive andreflective stack or layers of the present invention may comprisematerials or coatings other than ITO, ICO, IO, IWO layers or coatings orthe like and silver or silver alloy layers or coatings, withoutaffecting the scope of the present invention. For example, asemi-conducting layer of doped zinc oxide, or a semi-conducting layer ofcadmium stannate, or a semi-conducting layer of titanium nitride orother titanium compound or the like may be used in the stack, withoutaffecting the scope of the present invention.

As shown in FIG. 3, the first and second substrates 22, 24 arepositioned in spaced-apart relationship with one another with anelectrochromic medium 40 disposed between semi-conductive layer 26 andsemi-conductive layer 36. The electrochromic medium 40 changes color ordarkens in response to electricity or voltage applied to or through thesemi-conductive layers 26 and 30 at either side of the electrochromicmedium. The electrochromic medium 40 disposed between the front and rearsubstrates 22, 24 may be a solid polymer matrix electrochromic medium,such as is disclosed in U.S. Pat. No. 6,154,306, which is herebyincorporated by reference herein, or other suitable medium, such as aliquid or solid medium or thin film or the like, such as the typesdisclosed in U.S. patent application, Ser. No. 09/793,002, entitledVIDEO MIRROR SYSTEMS INCORPORATING AN ACCESSORY MODULE, filed Feb. 26,2001, now U.S. Pat. No. 6,690,268, and in U.S. Pat. Nos. 5,668,663 and5,724,187, the entire disclosures of which are hereby incorporated byreference herein, without affecting the scope of the present invention.The electrochromic mirror element may utilize the principles disclosedin commonly assigned U.S. Pat. Nos. 5,140,455; 5,151,816; 6,178,034;6,154,306; 6,002,544; 5,567,360; 5,525,264; 5,610,756; 5,406,414;5,253,109; 5,076,673; 5,073,012; 5,117,346; 5,724,187; 5,668,663;5,910,854; 5,142,407 or 4,712,879, which are hereby incorporated hereinby reference, or as disclosed in the following publications: N. R.Lynam, “Electrochromic Automotive Day/Night Mirrors”, SAE TechnicalPaper Series 870636 (1987); N. R. Lynam, “Smart Windows forAutomobiles”, SAE Technical Paper Series 900419 (1990); N. R. Lynam andA. Agrawal, “Automotive Applications of Chromogenic Materials”, LargeArea Chromogenics: Materials and Devices for Transmittance Control, C.M. Lampert and C. G. Granquist, EDS., Optical Engineering Press, Wash.(1990), which are hereby incorporated by reference herein, and in U.S.patent application, Ser. No. 09/793,002, filed Feb. 26, 2001 bySchofield et al. for VIDEO MIRROR SYSTEMS INCORPORATING AN ACCESSORYMODULE, now U.S. Pat. No. 6,690,268, which is hereby incorporated hereinby reference. Reflective element 16 may also include a seal 41positioned around the outer portions of the layers 32, 34, 36 and theelectrochromic medium 40 to seal the layers and avoid corrosion of themetallic layer 34.

During operation, a voltage may be applied to reflective element 16 viabus bars 38 positioned around and engaging the outer edges of thesemi-conductive layers 26, 30 (FIG. 3). The voltage applied by bus bars38 is bled from semi-conductive layer 30 and through the layers 32, 34,36 to the electrochromic medium 40. The ISI layer 28 of the presentinvention preferably provides for reduced resistance through the layers,which provides for faster, more uniform coloration of the electrochromicmedium 40, since the electrons applied via bus bars 38 atsemi-conductive layer 30 may bleed through the semi-conductive layers32, 36 faster due to the enhanced conductivity in the conductive layers32, 36. Preferably, the ISI layer or stack 28 provides a sheetresistance of less than approximately 10 ohms per square, morepreferably less than approximately 5 ohms per square, and mostpreferably less than approximately 2 ohms per square. Desirably, andparticularly for larger area mirrors, the sheet resistance is less thanapproximately 1 ohm per square, such as in the range of approximately0.1 to 0.7 ohms per square.

In order to provide enhanced performance of the electrochromic element,each of the layers of the ISI layer or stack has substantialconductivity and none of the layers significantly retardelectron/electrical conductivity from one layer to the other throughoutthe stack, and, thus, do not impede the flow of electrons into theelectrochromic (EC) medium. In this regard, it is desirable that one ormore of the metallic layers comprises a metallic material (which ispreferably a highly reflective material, such as silver or silver alloysor the like) having a specific resistivity of preferably less thanapproximately 5×10⁻⁵ ohm.cm, more preferably less than approximately1×10⁻⁵ ohm.cm, and most preferably less than approximately 5×10⁻⁶ohm.cm. Preferably, such a highly conductive metallic layer or layersis/are sandwiched between two non-metallic, partially conducting layers,preferably formed of a non-metallic material (such as a semi-conductingoxide, such as indium oxide, tungsten oxide, tin oxide, doped tin oxideor the like) having a specific resistivity of less than approximately1×10⁻² ohm.cm, more preferably less than approximately 1×10⁻³ ohm.cm,and most preferably less than approximately 5×10⁻⁴ ohm.cm.

In the illustrated embodiment of FIGS. 3 and 4, first semi-conductivelayer 30 is deposited on inward surface 24 a of second substrate 24. Thesemi-conductive layer 30 may be deposited on the glass or substrate 24via any suitable process. The particular thickness of the conductivelayer may vary depending on the particular application of reflectiveelement 16, as discussed below. In the illustrated embodiments of FIG.2-4, the semi-conductive layer 30 need not be transparent and maycomprise a chromium layer or the like. However, the semi-conductivelayer 30 may comprise a generally transparent semi-conductive layer ofcoating, such as a tin oxide layer, an indium tin oxide (ITO) layer orthe like, without affecting the scope of the present invention. In apreferred embodiment, semi-conductive layer 30 may comprise a chromiumlayer on surface 24 a of second substrate 24.

The transparent semi-conductive layers 32 and 36 of ISI layer 28 onsecond substrate 24 may comprise non-metallic transparent electricallyconducting or semi-conducting materials, such as tin oxide, indiumoxide, indium cerium oxide, indium tungsten oxide, nickel oxide,tungsten oxide, indium tin oxide, half-wave indium tin oxide, full waveindium tin oxide, doped tin oxides, such as antimony-doped tin oxide andfluorine-doped tin oxide, doped zinc oxides, such as antimony-doped zincoxide and aluminum-doped zinc oxide, and/or the like. Both of thesemi-conductive layers 32, 36 may comprise the same type of material forease of manufacturing, as discussed below.

Metallic layer or coating 34 comprises a thin film or layer of metal,such as silver, aluminum, or alloys thereof, or the like, with aselected thickness to provide sufficient reflectivity and/ortransmissivity, as discussed below. The selected metallic material maycomprise silver, but may otherwise comprise a material selected fromaluminum, silver alloys, aluminum alloys (such as 6061 or 1100 aluminumalloys or the like), manganese, chromium or rhodium, or any othermetallic material which is sufficiently reflective and/or transmissiveat a selected thickness. The thickness of metallic layer 34 ispreferably selected to be thick enough (such as approximately 60-100 nmor 600-1000 Å) to be substantially reflective and not transmissive, suchthat the ISI layer 28 is substantially opaque or non-transparent.

In a preferred embodiment, the semi-conductive layer 30 comprises indiumtin oxide (ITO) and is deposited onto surface 24 a of substrate 24 via ahot deposition process, involving, for example, sputter deposition ontoa heated substrate, with the heated substrate often being heated to atemperature of greater than about 200° C., sometimes greater than 300°C., as is known in the art. The combination of the semi-conductive layer30 on the substrate 24 defines a conductive substrate which may be usedfor various embodiments of the present invention, as discussed below.

The semi-conductive layer 32 of ISI layer 28 may be deposited ontosemi-conductive layer 30 via a cold deposition process, such as sputtercoating or the like onto an unheated substrate. Preferably, each of thelayers 32, 34, 36 of ISI layer 28 is deposited on second substrate 24 bya sputter deposition process. More particularly, the substrate 24(including the semi-conductive layer 30 already deposited thereon) maybe positioned in one or more sputter deposition chambers with eitherplanar or rotary magnetron targets, and with deposition of the layersbeing achieved by either reactive deposition of an oxide coating bysputtering from a metal target (or from a conductive, pressed oxidetarget) in an oxygen-rich atmosphere, or by DC sputtering from an oxidetarget, such as an IO, IWO, ITO or ICO target or the like. For example,the substrate 24 may be sputter coated with two targets in a singlechamber, such as by depositing the ITO layer 32 on semi-conductive layer30, turning or flipping the targets for sputter coating of the metalliclayer 34, and then turning the targets back to deposit the second ITOlayer or passivation layer 36 on the metallic layer 34. With such aprocess, it is important that the two ITO layers 30, 34 comprise thesame conductive material. Alternately, two targets may be positioned ina row, such that the substrate 24 is moved from one target (for thefirst ITO coating) to the other (for the metallic coating) and then backto the first (for the second ITO coating). It is further envisioned thatthree targets may be positioned in a row, with each target depositingthe layer in order on the substrate (in which case it would not be asimportant to have the semi-conductive or ITO layers 32, 36 comprise thesame material). Other processes for applying or depositing layers ofconductive material or layers and metallic material or layers may beimplemented, without affecting the scope of the present invention. Inthe illustrated embodiment of FIGS. 2 and 3, semi-conductive layer 30may be deposited or applied to substantially the entire surface 24 a ofsubstrate 24, while the outer region or edge of semi-conductive layer 30and substrate 24 may be masked during the deposition process so thatlayers 32, 34, 36 do not cover the outer edge of substrate 24 andsemi-conductive layer 30.

Because the embodiment of the reflective element of the presentinvention illustrated in FIG. 4 does not include a display on demand orother type of display transmitting or projecting through theelectrochromic reflective element, it is desirable to have a thickmetallic or silver layer 34, such as in a range of approximately 60-100nm (600-1000 Å), because the metallic layer does not have to betransmissive of any light therethrough. It is also unnecessary for thesecond substrate to be transparent. However, it is desirable to avoidtinting or color interference affects as seen in reflection from thereflector (which may arise when stacking layers of conductive coatingsand/or metallic coatings on top of one another), because it is desirableto have a neutral or non-colored/non-tinted reflector when no voltage isapplied across the electrochromic medium.

Optionally, the metallic layer may be absent or removed at portions,such as to create a local window for placement therebehind of a lightemitting display, such as a compass display or PSIR display or otherinformational display or the like, such as a display of the typedisclosed in commonly assigned U.S. Pat. Nos. 6,222,460 and 6,326,900,which are hereby incorporated herein by reference in their entireties,but while maintaining at least the underlying semi-conducting ITO layerat the local window region so that electrical connection through theelectrochromic medium at that local region is sustained. In this regard,it is preferable to have an ITO underlayer with a sheet resistance ofless than approximately 80 ohms per square, more preferably less thanapproximately 25 ohms per square, and most preferably less thanapproximately 15 ohms per square.

In order to avoid such undesirable tinting or color interferenceaffects, such as yellow tinting or other color tinting of the compoundor stacked reflective element, as seen in the reflection when theelectrochromic reflective element is unpowered, the physical thicknessesof the conductive layers and the metallic layer are selected to providea desired combination of layer thicknesses to achieve the desiredresults. For example, the ISI layer 28 may include an adhesion layer orundercoating semi-conductive layer 32 of approximately 100 Å+/−50 Å ofITO or the like, a silver layer 34 of approximately 800 Å+/−200 Å and apassivation semi-conductive layer 36 of approximately 120 Å+/−25 Å ofITO or the like, which provides a desired result with minimal yellowtinting or other color tinting or color interference affects as seen inthe reflection.

The range of thicknesses of the layers may be selected to provide adesired untinted affect in the reflection, such that the reflectiveelement may be spectrally tuned to provide a desired reflectant untintedappearance. Testing of various embodiments has shown that thethicknesses of the layers may vary by approximately 25 percent or morefrom a desired or targeted dimension, yet will still provide the desiredresults. Such tolerances significantly ease the processing of the ISIlayer, since this is well within the capability of typical sputtercoating equipment. The layers of the reflective element and ISI stackmay be selected such that the reflective element provides asubstantially spectrally untinted reflection when viewed by a driver orpassenger in the vehicle when no voltage is applied across theelectrochromic medium. Also, the layers may be selected and combined toexhibit a spectrally selective transmissive characteristic, which isestablished by the refractive indices and physical thicknesses of thelayers disposed between the electrochromic medium and the third surfaceof the second substrate.

Although the above embodiment provides a desired neutral color/tint forthe reflector, if the passivation layer 36 is increased in thickness,the reflector may become tinted or yellowed. However, if the passivationlayer is further increased in thickness to approximately 680 Å, then thenon-tinting is approximately the same as when the passivation layer hasa thickness of approximately 120 Å. This periodic change in tintingaffect in response to the thicknesses of the layers or coatings of theISI layer of the present invention allows for selection of differentthicknesses of the layers depending on the particular application anddesired result of the electrochromic reflective element of the presentinvention.

Referring now to FIGS. 5 and 6, a reflective element 116 may havealternating layers or an ISI stack or layer 128 comprising a firstsemi-conductive layer or adhesion layer 132 deposited or sputter coateddirectly onto surface 24 a of second substrate 24, a metallic layer 134deposited on semi-conductive layer 132, and a second semi-conductivelayer or passivation layer 136 deposited on metallic layer 134. Thesecond or rear substrate 24 is masked around substantially the entireouter region 24 c of surface 24 a during the deposition process, suchthat the ISI layer 128 is not deposited in the masked region 24 c.However, the substrate is not masked over the entire outer edge orregion of substrate 24, in order to allow deposition of the ISI layer ata particular area, such that a tab-out portion or area 131 is formed inthe ISI layer 128. The tab out area 131 facilitates electricalconnection with the conductive coatings 132, 134, 136, such that thefirst semi-conductive layer 30 of reflective element 16 is not required.In a preferred embodiment of the present invention, the reflectiveelement 116 may include a semi-conductive layer 132 of an ITO coatingwhich has a thickness of approximately 100 Å+/−25 Å, a silver layer 134having a thickness of approximately 900 Å+/−100 Å, and a secondsemi-conductive layer 136 of ITO or the like having a thickness ofapproximately 120 Å+/−25 Å. Such an arrangement of semi-conductivelayers and a sandwiched metallic layer provides a neutral reflectancewith minimal tinting or color interference affects as seen inreflectance and with the electrochromic medium unpowered.

The opaque ISI layer 28, 128 and the third surface reflective element ofthe present invention therefore provides an economical, low costelectrochromic reflective element, which provides a neutral colorreflection. Typically, for a sputter coating operation, a range ofwithin +/−5% of a nominal target for uniformity of coating is desired.However, in the present invention, the uniformity tolerance isapproximately +/−25% for each of the coatings or layers from cell tocell. The ISI layer on the second substrate thus may be easy and fast tomanufacture due to the thicknesses and the tolerances for the thicknessof each particular coating.

Referring now to FIGS. 7 and 8, a mirror assembly 210 in accordance withthe present invention (shown as an interior rearview mirror assembly inFIG. 7; however, the reflective element 216 may be implemented at anexterior mirror assembly or other mirror assembly, without affecting thescope of the present invention) may include a display system or element218 which is operable to provide, emit or display information or lightthrough a mirror element or reflective element 216 of the mirrorassembly. The light is emitted through the reflective element 216 at adisplay area 220 of mirror assembly 210, such that the displayinformation or light is viewable by a driver of the vehicle. Thereflective element 216 includes first (or front) and second (or rear)substrates 222, 224, and a conductive and transmissive ISI stack orlayer or DOD stack or layer 228 disposed on the inward surface 224 a ofthe second substrate (or the third surface of the reflective element).The second substrate 224 and ISI layer 228 comprise a transflective oneway mirror, such as disclosed in commonly assigned U.S. patentapplication, Ser. No. 10/054,633, filed Jan. 22, 2002 by Lynam et al.for VEHICULAR INTERIOR LED LIGHTING SYSTEM, now U.S. Pat. No. 7,195,381,which is hereby incorporated herein by reference. Preferably, the mirrorreflective element (behind which the display is disposed so that theinformation displayed is visible by viewing through the mirrorreflective element) of the mirror assembly comprises a transflectivemirror reflector, such that the mirror reflective element issignificantly transmitting to visible light incident from its rear(i.e., the portion furthest from the driver in the vehicle), whilesimultaneously the mirror reflective element is substantially reflectiveto visible light incident from its front (i.e. the position closest tothe driver when the interior mirror assembly is mounted in the vehicle).The transflective electrochromic reflective mirror element (such as isdisclosed in U.S. patent application, Ser. No. 09/793,002, entitledVIDEO MIRROR SYSTEMS INCORPORATING AN ACCESSORY MODULE, filed Feb. 26,2001, now U.S. Pat. No. 6,690,268 and in U.S. Pat. Nos. 5,668,663 and5,724,187, the entire disclosures of which are hereby incorporated byreference herein) comprises an electrochromic medium sandwiched betweenthe first and second substrates.

The ISI stack or layer 228 includes a conductive metallic layer 234,which is thin enough to be sufficiently transparent or transmissive toallow the display information to be transmitted through the ISI or DODlayer 228 and through reflective element 216 for viewing by the driverof the vehicle. As the thickness of the metallic layer 234 decreases,the transmissivity increases, but the reflectivity decreases. Therefore,a desired thickness of the metallic layer (along with a desiredthickness of the other layers of the ISI stack or layer) must beselected to provide sufficient reflectivity and transmissivity, asdiscussed below. Because the metallic layer 234 is at least partiallytransmissive, it is desirable to provide an opaque coating or tape orthe like 225 on an outer surface 224 b of second substrate 224 (or thefourth surface of the reflective element 216). The coating or tape 225may be a black tape or other color tape or coating.

Display system 218 preferably comprises a display on demand type ofdisplay and includes a display element or light emitting device 218 apositioned at the back surface 224 b of second substrate 224. Displayelement 218 a is operable to emit light, such as in the form of indicia,alphanumeric characters, images, or the like, in response to a controlor input. Display element 218 a may be a vacuum fluorescent (VF) displayelement, a light emitting diode (LED) display element, an organic lightemitting diode (OLED) display element, a gas discharge display element,a plasma display element, a cathode ray tube display element, a backlitactive matrix LCD screen, an electroluminescent display element, a fieldemission display element or the like, without affecting the scope of thepresent invention. The particular display element may be selected toprovide a desired color to the display. For example, a VF displayelement may provide a blue-green color or other colors to theinformation displayed (depending on the phosphor selected for thedisplay), while a light emitting diode display element may provide othercolors, such as reds, ambers, or other colors to the informationdisplayed.

Preferably, the display is a display-on-demand type of display, such asof the type disclosed in commonly assigned U.S. Pat. Nos. 5,668,663 and5,724,187, and/or in U.S. patent applications, Ser. No. 10/054,633,filed Jan. 22, 2002 by Lynam et al. for VEHICULAR INTERIOR LED LIGHTINGSYSTEM; now U.S. Pat. No. 7,195,381, and Ser. No. 09/793,002, filed Feb.26, 2001 by Schofield et al. for VIDEO MIRROR SYSTEMS INCORPORATING ANACCESSORY MODULE, now U.S. Pat. No. 6,690,268, which are all herebyincorporated herein by reference. With such a display, it is not onlydesirable to adjust the display brightness according to ambient lightingconditions, but it is also desirable to adjust the display brightnesssuch that a sufficient contrast ratio is maintained against the variablebackground brightness of the reflected scene. Also, it may be desirableto compensate for changes in transmission of the electrochromic deviceeffected to control rearward glare sources, so that the displaybrightness appears to be maintained at a generally constant level.

It is envisioned that the display 218 may include a filter or spectralelement 217 positioned between the illumination source or displayelement 218 a of the display 218 and the outer or fourth surface 224 bof second substrate 224. The filter 217 may function to filter out lighthaving a wavelength outside of the desired band of light being emittedby the display element or, in other words, the filter or spectralelement 217 may transmit a band width of light that substantiallymatches the particular spectral output of the display or thatsubstantially matches a desired color for the display information. Bytransmitting only the spectral band which at least generally matches thespectral output of the display device, the filter functions to filterout ghost images of the display, where ambient light may enter thedisplay, such that the display characters may be visible through thereflective element when the display is off.

Because the reflectivity of the metallic layer 234 provides sufficientreflectance over its entire surface (i.e., there are no “windows” formedin or through the metallic layer), mirror assembly 210 may include otherdisplays or multiple display on demand type displays, or other types ofdisplays, such as one or more “display on need” type displays or thelike. For example, one or more display on need type displays 213 (FIG.7) may be provided, such as to indicate to the driver of the vehiclethat a door of the vehicle is ajar, or that the driver's seat belt isnot fastened, or any other condition or status that may be important tothe driver or occupant of the vehicle. The display on need type displayor displays may provide indicia, alphanumeric characters, symbols, orthe like via one or more light emitting sources (not shown) behind thesecond substrate in a similar manner as display system 218 discussedabove, and may include a filter (also not shown) for filtering out lightthat is not within the desired spectral band of the particular displaysystem.

In the illustrated embodiment of FIG. 8, ISI or DOD layer or stack 228includes a first semi-conductive layer 230, a second semi-conductivelayer or adhesion layer 232, a reflective and transmissive metalliclayer 234 and a semi-conductive or passivation layer 236. Similar to ISIlayer 28, discussed above, semi-conductive layer 230 may be deposited orapplied to substantially the entire surface 224 a of substrate 224,while the outer region or edge of semi-conductive layer 230 andsubstrate 224 may be masked during the deposition process so that thelayers 232, 234, 236 do not cover the outer edge of substrate 224 andsemi-conductive layer 230.

Preferably, the physical thicknesses and materials of the metallic layer234 and the semi-conductive layers 230, 232 and 236 are selected toprovide sufficient transmissivity of at least a particular spectral bandor range of wavelengths of light which generally matches the peakintensity spectral band of light being emitted by the display. Suchspectral tuning or matching of the layers to the display allows thedisplay information to transmit through the reflective element forviewing of the display information by the driver of the vehicle, whilealso providing sufficient reflectivity over the entire reflectiveelement, and while minimizing the tinting or color interference affectson the reflected image (or targeting such tinting affects toward adesired color). Preferably, the light transmission of the particularspectral band through the reflective element is greater thanapproximately 15 percent and the reflectivity of the reflective elementto other wavelengths of light is greater than approximately 80 percent.More preferably, the light transmission of the particular spectral bandis greater than approximately 20 percent, and most preferably greaterthan approximately 25 percent.

The reflective element 216 is spectrally tuned to maximizetransmissivity of a particular desired or targeted range or ranges ofwavelengths or spectral bands and to substantially reflect or nottransmit other wavelengths of light. The particular choices orthicknesses/materials of the layers is influenced by the spectralemission of the display being used in the mirror assembly. In oneexemplary embodiment of the present invention, a transmissive ISI or DODlayer or stack 228 includes a metallic layer 234 of approximately 350 Åsandwiched between a semi-conductive passivation layer 236 ofapproximately 68 nm (680 Å) and a semi-conductive adhesion layer 232 ofapproximately 41 nm (410 Å). The adhesion layer 232 is deposited on asemi-conductive layer 230 having a thickness of approximately 30 nm (300Å). In this embodiment, the ISI layer 228 is spectrally tuned fortransmission of an orange light (having a peak intensity wavelength inthe range of approximately 600 nm) emitting from display device 218 a.

In certain conditions, the ambient light intensity within the cabin ofthe vehicle may be sufficiently high so that reflected light from themirror reflective element and, in particular, from the display region220, tends to “wash-out” the display. It is envisioned that this glaremay be reduced by taking advantage of the electrochromic function of themirror assembly. More particularly, the electrochromic medium 240 of theelectrochromic mirror reflective element 216 may be colored or darkenedin the area of the display by constructing a locally addressable regionacross the display (as shown at 220, 220 a of FIG. 7). This may beachieved by creating a deletion line in the second surfacesemi-conductive layer 226 at the second surface of the first or frontsubstrate 222 (FIG. 8) and/or in the third surface semi-conductive layer230 (or a third surface semi-conductive layer of the type shown in FIG.9 and described below at 332), hence breaking electrical continuity fromthe rest of the electrochromic cell. An ambient light sensor (not shown)may be used to detect the critical ambient light levels at which“wash-out” is a problem. The addressable region may then be separatelycolored or darkened to the appropriate level to reduce the glare fromthe display area in response to the ambient light sensor. Although sucha glare problem could be solved by coloring the entire mirror, bylocalizing the region of coloration to only the display area, theelectrochromic mirror assembly of the present invention allows the restof the mirror reflective area, which does not incorporate the display,to retain full reflectivity while the display area is colored ordarkened (such as may be useful when driving by day).

In another exemplary embodiment of the present invention, a transmissiveISI or DOD layer includes a metallic layer 234 of approximately 40 nm(400 Å) sandwiched between a semi-conductive passivation layer 236 ofapproximately 43 nm (430 Å) and a semi-conductive adhesion layer 232 ofapproximately 10 nm (100 Å). The semi-conductive adhesion layer 232 isdeposited on an adhesion or semi-conductive layer 230 having a thicknessof approximately 30 nm (300 Å). In this embodiment, the ISI or DOD layer228 is spectrally tuned for spectrally selective transmission of ablue-green light (having a peak intensity wavelength of approximately505 nm) emitting from display device 218 a.

The thickness of the first semi-conductive layer 230 may be the same foreach embodiment described above (and for the particular embodimentsdiscussed below, such as with respect to FIGS. 10-17), in order toprovide a common conductive substrate (including the semi-conductivelayer 230 already deposited or coated on the surface of the substrate)for the different particular applications of the substrate and ISIlayers of the present invention. This may ease the manufacturing of thereflective elements, since the same hot ITO coating or the like may beapplied to common substrates for various applications, and then theconductive substrates may be coated with different thickness layers ofconductive and metallic coatings for different applications of thereflective element (such as for mirrors having different coloreddisplays).

As discussed above with respect to ISI layer 128, and with reference nowto FIG. 9, a second substrate 324 may have an ISI or DOD layer 328 onits inward or forward surface 324 a which may include layers 332, 334,336 which may have a tab-out portion 331 for electrical connections, soas to not require the first conductive layer, without affecting thescope of the present invention. Because the metallic layer 334 is thinand not as conductive as the metallic layer 134, discussed above, thetab-out portion 331 of ISI layer 328 is preferably substantially largerin size or width than the tab-out portion 131 may have been for ISIlayer 128. In a particular exemplary embodiment of the substrate 324 andISI layer 328 of a reflective element as shown in FIG. 9, where theconductive layer 332 is deposited directly on the surface 324 a ofsubstrate 324, the ISI layer 328 may include a metallic layer 334 ofapproximately 35 nm (350 Å) sandwiched between a passivation layer 336of approximately 70 nm (700 Å) and an adhesion layer 332 ofapproximately 70 nm (700 Å). This combination or stack of layers on theglass or substrate 324 provides a transflective reflective element whichis at least approximately 20 percent transmissive and which isspectrally tuned to pass a particular band of light being emitted bydisplay device 218 a of display system 218. In this particularembodiment, the transflective reflective element is spectrally tuned topass light having a peak intensity wavelength of approximately 605nanometers, while substantially reflecting other light.

Other thicknesses and materials of the layers may be selected fordifferent displays having different colors or wavelengths of emittedlight, without affecting the scope of the present invention. Thethicknesses and particular materials of the layers of the ISI or DODstack and transflective reflector are selected such that theircombination provides enhanced or substantial transmissivity of thespectral band or bands corresponding to the spectral band of lightemitted by the particular display implemented in the reflective element,while providing substantial reflectance of other visible light.

Referring now to FIG. 10, a second substrate 424 of a reflective elementmay have multiple layers or a double ISI or DOD layer or stack 428applied to inward surface 424 a. Double ISI layer 428 includes a firstsemi-conductive layer 430 applied to or deposited on inward surface 424a, a second semi-conductive or adhesion layer 432 a deposited onsemi-conductive layer 430, a first metallic layer 434 a deposited onsemi-conductive layer 432 and another semi-conductive layer 436 adeposited on metallic layer 434 a. Double ISI layer 428 further includesa second metallic layer 434 b deposited on semi-conductive layer 436 awith another semi-conductive layer 436 b deposited on second metalliclayer 434 b. Therefore, the ISI stack or layer 428 is an alternatingstack or combination of dielectric or transparent semi-conductive layersand metallic layers, whereby each metallic layer is sandwiched between arespective pair of conductive or semi-conductive non-metallic layers.

Such an arrangement may be used to provide a desired amount or increasedamount of spectrally selective transmission of one or more particularspectral bands of light through the ISI or DOD layers, while increasingthe reflectivity or maintaining the reflectivity of the ISI or DODlayers with respect to other spectral bands of light over the single ISIor DOD stack designs discussed above. More particularly, the doublestack arrangement (or more layers if desired) provides for increasedtransmission of a narrower spectral band of light, which allows thereflective element to transmit a high percentage (such as greater thanapproximately 50 percent transmissivity) of a selected narrow spectralband of light. The narrow spectral band is selected so as to besubstantially pinpointed or targeted at the particular peak intensitywavelength or wavelengths of light being emitted by the display device.Such an arrangement is particularly suitable for use with displaydevices incorporating light emitting diodes, which may emit light withina particular, narrow spectral band. The particular thickness andmaterial for each layer or coating may be selected depending on theparticular application and desired results.

For example, in a single ISI or DOD stack design which providesapproximately 20-25 percent transmissivity of a particular spectral bandor range, the reflectance of the ISI layer may be approximately 60-70percent with respect to other light. If it is desired that the mirrorhave approximately 70 percent photopic reflectance or higher andincreased transmissivity of a desired spectral band of light, a doubleISI or DOD stack may be implemented. One particular embodiment of such adouble ISI stack provides a semi-conductive layer (430 and/or 432) ofapproximately 71 nm (such as a layer 430 of approximately 30 nm (300 Å)and a layer 432 a of approximately 41 nm (410 Å) or other combinations)of ITO or the like, a first metallic layer 434 a of approximately 41 nm(410 Å), a semi-conductive layer 436 a of approximately 101 nm (1010 Å)of ITO or the like, a second metallic layer 434 b of approximately 36 nm(360 Å) and a semi-conductive layer 436 b of approximately 10 nm (100 Å)of ITO or the like. This embodiment provides increased reflectivity ofthe reflective element to most wavelengths of light, while achieving thedesired amount of transmissivity of the particular, targeted spectralband or bands. This is because the two metallic layers 434 a, 434 b,which are generally planar and parallel to each other, are separated bya distance of the order of approximately 100 nm (1000 Å), which givesrise to multiple beam interference of the incident light, resulting inconstructive interference at certain wavelengths and destructiveinterference at other wavelengths. This particular example provides areflective element which is spectrally tuned to substantially transmitlight with a wavelength of approximately 602 nanometers, whilesubstantially reflecting other visible light.

Other materials (with other refractive indices) and other physicalthicknesses for the layers may be selected to transmit other desiredwavelengths or ranges of wavelengths, without affecting the scope of thepresent invention. Also, additional repeating layers may be added toform a multiple stack, such as an additional metallic conducting layerand an additional semi-conductive ITO layer (or the like), in order toachieve the desired affect. The repeating and alternating layers form anarrow band ISI stack (which may have seven or nine or more layers ofconductive layers and metallic layers), which functions to pass ortransmit only such light which corresponds to one or more particular,substantially narrow spectral bands or ranges of wavelengths. Theadditional layers may provide enhanced performance of the reflectiveelement with only an incremental increase in cost, since the additionallayers are preferably deposited onto the other layers as part of thesputter coating process. With each additional set or stack of layers,each of the reflective, metallic layers may be reduced in thickness,which may provide increased transmissivity through the stack for atargeted spectral band, while still providing the desired amount ofreflectivity over the reflective element. For example, a nine layer ISIor DOD stack (such as shown in FIG. 17 and discussed below) may providea reflective element that has a greater than approximately 60 percenttransmissivity of one or more particular, narrow spectral bands, andwhich is tuned or substantially pinpointed to match the emissionspectrum from a particular display device (such as a display deviceincluding a light emitting diode).

Referring now to FIGS. 11-17, several particular examples of areflective element or mirror element in accordance with the presentinvention are shown. The reflective elements of FIGS. 11-17 incorporatethe design and functional aspects of the reflective elements discussedabove, and are provided as specific examples or embodiments of thepresent invention. The materials and physical thicknesses of the layersare selected to provide different refractive indices and thicknesses toprovide different beam interference of the incident light, therebyresulting in the desired transmissive range for a particular displayelement. In each embodiment of FIGS. 11-17, the various layers andsubstrates are given similar reference numbers as shown with respect tothe reflective elements shown in FIGS. 2-10, but with each embodimentadding 100 to the reference numbers of the previous embodiment. Clearly,the scope of the present invention includes other combinations of layersthat may be implemented to provide for enhanced transmissivity of one ormore particular spectral bands of light, while providing substantialreflectance of other light.

With reference to FIG. 11, a reflective element 516 has a frontsubstrate 522 and a rear substrate 524 and a display element 518 at arear or fourth surface of rear substrate 524. A semi-conductive ITOlayer (or the like) 530 of approximately 30 nm is deposited on theforward or third surface of rear substrate 524, while a semi-conductivelayer 526 (such as ITO, tin oxide or the like) is deposited on the rearor second surface of front substrate 522. An ISI or DOD stack or layer528 and an electrochromic (EC) medium 540 and seal 541 are providedbetween the semi-conductive layers 526, 530. ISI layer 528 comprises asubstantially transparent semi-conducting non-metallic adhesion layer532 of approximately 41 nm of ITO, ICO, IWO or the like, a metallicconducting layer 534 of approximately 35 nm of silver or silver alloy orthe like, and a substantially transparent semi-conducting non-metallicpassivation layer 536 of approximately 68 nm of ITO, ICO, IWO or thelike. As shown in FIG. 11A, such a configuration provides atransmissivity of light through reflective element 516 with a peaktransmissivity of light having a wavelength of approximately 580 nm. Thetransflective reflector of the reflective element 516 is thus spectrallytuned to transmit orange light, such as light emitted from an orangevacuum fluorescent display 518, which emits light having a peakintensity of approximately 580 nm, as shown in FIG. 11B. The display 518may also include a color filter 517, such as discussed above withrespect to display 218.

In another particular embodiment similar to that of FIG. 11, anautomotive DOD electrochromic mirror cell may include a transparentconductive layer, such as an ITO layer or the like (having, for example,approximately 12 ohms per square resistivity, which is commerciallyavailable as an ITO coated substrate), at the innermost, second surfaceof the front substrate, and a three layer coating or stack deposited ona transparent conductive layer, such as an ITO layer, at the rearsubstrate, itself deposited on the inner facing third surface of therear substrate in a front/rear twin substrate laminate cellconstruction. The ITO layer at the rear substrate layer may have, forexample, approximately 80 ohms per square resistivity, and the rearsubstrate may be a commercially available ITO coated substrate. Thethree layer stack or layers may be applied to the appropriate ITO coatedsurface of the rear substrate, such as via sputter coating or the like.For example, the rear glass element or substrate may be placed in acoating mask fixture to mask the perimeter and may be placed in a vacuumdeposition system. The transflective third surface reflector/conductormay be made on or applied to the intended surface of the rear substrate(or to the ITO layer on the “third surface”) by sequentially depositingfirst approximately 41 nm of ITO, second approximately 40 nm of silvermetal and third approximately 65 nm of ITO onto the ITO layer at thethird surface of the rear substrate.

The front and rear substrates are spaced apart using an epoxy perimeterseal (as is known and practiced in the electrochromic mirror art) withthe conductive surfaces facing each other and preferably with an offsetfor the purpose of attaching an electrode clip or busbar. The spacingbetween the conductive planar surfaces is, for example, approximately 90μm. After curing of the epoxy seal, the reflective element may be vacuumfilled with an electrochromic medium, such as an electrochromic monomermaterial or the like. After filling the reflective element with theelectrochromic monomer, the filling port of the reflective element orcell may be plugged with a UV curable adhesive which may then be curedby exposure to UV radiation. The reflective element or cell may then becured in an oven to form a solid polymer matrix electrochromic medium.

When such an embodiment was formed and tested, a voltage ofapproximately 1.2 volts was applied to the reflective element and it wasobserved to color rapidly and uniformly. The photopic reflectance of thereflective element was initially approximately 67%, with a neutralsilvery appearance, and decreased to approximately 7% in less thanapproximately 8 seconds with the voltage applied. The transmittance ofthe reflective element in its bleached state was approximately 19% forlight having wavelengths between approximately 600 nm and 620 nm. Whenthe voltage was disconnected or stopped, the reflectance of thereflective element substantially uniformly returned to its originalvalue of approximately 67% within about 10 seconds. The DOD stack of thepresent invention thus may provide for enhanced transmittance of lighthaving a preselected wavelength or range or band of wavelengths, evenwhen in the bleached or colored or darkened state.

It is further envisioned that one or more adhesion enhancement layers orpassivation layers, such as a layer or layers of nichrome (NiCr),palladium (Pd), platinum (Pt) or the like, may be applied or disposed atone or both sides of the metallic or silver layer 534, in order toincrease the corrosion resistance of the metallic layer and to enhancethe adhesion and the mechanical stability of the metallic layer. Forexample, an adhesion or passivation layer may be applied or disposedbetween metallic layer 534 and semi-conductive layer 532, and anotheradhesion or passivation layer may be applied or disposed betweenmetallic layer 534 and semi-conductive layer 536. The adhesion orpassivation layer or layers may have a thickness of approximately 0.5 nmto approximately 10 nm or thereabouts. The adhesion or passivationlayers may be disposed at one or both sides or surfaces of the metalliclayer or layers of any of the reflective element embodiments describedherein or of other types of electrochromic reflective elements, withoutaffecting the scope of the present invention. Such adhesion orpassivation layers may be applied at the metallic layer or layers ofother stacks or layers of the present invention described herein.

With reference to FIG. 12, a reflective element 616 has a frontsubstrate 622 and a rear substrate 624 and a display element 618 at arear or fourth surface of rear substrate 624. A semi-conductive ITOlayer (or the like) 630 of approximately 30 nm is deposited on theforward or third surface of rear substrate 624, while a semi-conductivelayer 626 (such as ITO, tin oxide or the like) is deposited on the rearor second surface of front substrate 622. An ISI or DOD stack or layer628 and EC medium 640 and seal 641 are provided between thesemi-conductive layers 626, 630. ISI layer 628 comprises an adhesionlayer 632 of approximately 10 nm of ITO, ICO, IWO or the like, ametallic layer 634 of approximately 40 nm of silver or silver alloy orthe like, and a passivation layer 636 of approximately 43 nm of ITO,ICO, IWO or the like. As shown in FIG. 12A, such a configurationprovides a transmissivity of light through the reflective element with apeak transmissivity of light having a wavelength of approximately 500nm. The reflective element 616 is thus spectrally tuned to transmitlight emitted from a blue-green vacuum fluorescent display 618, whichmay emit light having a peak intensity of approximately 500 nm, as shownin FIG. 12B.

With reference to FIG. 13, a reflective element 616′ provides asubstantially spectrally neutral transmission characteristic and has afront substrate 622′ and a rear substrate 624′ and a display element618′ at a rear or fourth surface of rear substrate 624′. Asemi-conductive ITO layer (or the like) 630′ of approximately 30 nm isdeposited on the forward or third surface of rear substrate 624′, whilea semi-conductive layer 626′ (such as ITO, tin oxide or the like) isdeposited on the rear or second surface of front substrate 622′. An ISIor DOD stack or layer 628′ and EC medium 640′ and seal 641′ are providedbetween the semi-conductive layers 626′, 630′. ISI layer 628′ comprisesan adhesion layer 632′ of approximately 78 nm of ITO, ICO, IWO or thelike, a metallic layer 634′ of approximately 31 nm of silver or silveralloy or the like, and a passivation layer 636′ of approximately 63 nmof ITO, ICO, IWO or the like. As shown in FIG. 13A, such a configurationprovides a generally neutral transmission of light through thetransflective reflective element for most wavelengths of visible light.

With reference to FIG. 14, a reflective element 716 has a frontsubstrate 722 and a rear substrate 724 and a display element 718 at arear or fourth surface of rear substrate 724. A semi-conductive ITOlayer (or the like) 730 of approximately 30 nm is deposited on theforward or third surface of rear substrate 724, while a semi-conductivelayer 726 (such as ITO, tin oxide or the like) is deposited on the rearor second surface of front substrate 722. A double stack ISI or DODstack or layer 728 and EC medium 740 and seal 741 are provided betweenthe semi-conductive layers 726, 730. Double stack ISI layer 728comprises a semi-conductive adhesion layer 732 of approximately 60 nm ofITO, ICO, IWO or the like, a first metallic layer 734 a of approximately33 nm of silver or silver alloy or the like, a semi-conductive layer 736a of approximately 117 nm of ITO, ICO, IWO or the like, a secondmetallic layer 734 b of approximately 33 nm of silver, silver alloy orthe like, and a semi-conductive layer 736 b of approximately 86 nm ofITO, ICO, IWO or the like. As shown in FIG. 14A, such a configurationprovides a transmissivity of light through the reflective element with apeak transmissivity of light having a wavelength of approximately 650nm. The reflective element 716 is thus spectrally tuned to transmit redlight, such as light emitted from a red light emitting diode display718, which may emit light having a peak intensity of approximately 650nm, as shown in FIG. 14B. As can be seen with reference to FIGS. 14A and11A, the transflective reflector and double stack ISI or DOD layer 728provide a narrower band of transmissivity for the desired spectral bandor range of wavelengths being emitted by the display. Such aconfiguration thus may provide enhanced reflectivity of light outside ofthe targeted spectral band.

With reference to FIG. 15, a reflective element 816 has a frontsubstrate 822 and a rear substrate 824 and a display element 818 at arear or fourth surface of rear substrate 824. A semi-conductive ITOlayer (or the like) 830 of approximately 30 nm is deposited on theforward or third surface of rear substrate 824, while a semi-conductivelayer 826 (such as ITO, tin oxide or the like) is deposited on the rearor second surface of front substrate 822. A double stack ISI or DODstack or layer 828 and EC medium 840 and seal 841 are provided betweenthe semi-conductive layers 826, 830. Double stack ISI layer 828comprises a semi-conductive adhesion layer 832 of approximately 23 nm ofITO, ICO, IWO or the like, a first metallic layer 834 a of approximately30 nm of silver or silver alloy or the like, a semi-conductive layer 836a of approximately 204 nm of ITO, ICO, IWO or the like, a secondmetallic layer 834 b of approximately 34 nm of silver, silver alloy orthe like, and a semi-conductive layer 836 b of approximately 47 nm ofITO, ICO, IWO or the like. As shown in FIG. 15A, such a configurationprovides a transmissivity of light through the reflective element with apeak transmissivity of light having a wavelength of approximately 500nm. The reflective element 816 is thus spectrally tuned to transmitblue-green light, such as light emitted from a blue-green light emittingdiode display 818, which may emit light having a peak intensity ofapproximately 500 nm. Similar to double stack ISI layer 728 discussedabove, the transflective reflector and double stack ISI layer 828provide a narrower band of transmissivity for the desired spectral bandor range of wavelengths being emitted by the display. Such aconfiguration thus may provide enhanced transmissivity of thepreselected or targeted spectral band and enhanced reflectivity of lightoutside of the targeted spectral band.

With reference to FIG. 16, a reflective element 916 has a frontsubstrate 922 and a rear substrate 924 and a display element 918 at arear or fourth surface of rear substrate 924. A semi-conductive ITOlayer (or the like) 930 of approximately 30 nm is deposited on theforward or third surface of rear substrate 924, while a semi-conductivelayer 926 (such as ITO, tin oxide or the like) is deposited on the rearor second surface of front substrate 922. A multiple stack ISI or DODstack or layer 928, EC medium 940, seal 941 and encapsulant 943 areprovided between the semi-conductive layers 926, 930. The ISI or DODstack or layer 928 may be provided on ITO layer 930 so as to have a tabout portion as discussed above with respect to ISI layer 328. Theencapsulant 943 is provided along the edges of the tab out portion ofreflective element 916, and the seal 941 is provided between the tab outportion and the ITO layer 926 on front substrate 922 and between the ITOlayers 924, 926 around ISI layer 928 where there is no tab out portion.

Multiple ISI or DOD stack or layer 928 comprises an adhesion layer 932of approximately 80 nm of ITO, ICO, IWO or the like, a first metalliclayer 934 a of approximately 30 nm of silver or silver alloy or thelike, a layer 936 a of approximately 101 nm of silicon oxide or thelike, a layer 934 b of approximately 60 nm of titanium oxide or thelike, a layer 936 b of approximately 95 nm of silicon oxide or the like,a layer 934 c of approximately 161 nm of titanium oxide or the like, alayer 936 c of approximately 53 nm of silicon oxide or the like, ametallic layer 934 d of approximately 50 nm of silver or silver alloy orthe like, and a layer 936 d of approximately 72 nm of ITO, ICO or thelike. As shown in FIG. 16A, such a configuration provides atransmissivity of light through the reflective element with a peaktransmissivity of light having a wavelength of approximately 650 nm. Thereflective element 916 is thus spectrally tuned to transmit red light,such as light emitted from a red light emitting diode display 918, whichmay emit light having a peak intensity of approximately 650 nm. Thetransflective reflector and multiple stack ISI layer 928 provide anextra narrow band of transmissivity for the desired spectral band orrange of wavelengths being emitted by the display. Such a configurationthus may provide enhanced reflectivity of light outside of the targetedspectral band. As can be seen in FIG. 16A, reflective element 916 mayalso transmit spectral bands of light at certain other wavelengths orranges of wavelengths as well, such as at approximately 410 nm and 470nm.

With reference to FIG. 17, a reflective element 1016 has a frontsubstrate 1022 and a rear substrate 1024 and a display element 1018 at arear or fourth surface of rear substrate 1024. A semi-conductive ITOlayer (or the like) 1030 of approximately 30 nm is deposited on theforward or third surface of rear substrate 1024, while a semi-conductivelayer 1026 (such as ITO, tin oxide or the like) is deposited on the rearor second surface of front substrate 1022. A multiple stack ISI or DODstack or layer 1028, EC medium 1040, seal 1041 and encapsulant 1043(around a tab out portion of the ISI layer, as discussed above) areprovided between the semi-conductive layers 1026, 1030.

Multiple stack ISI or DOD layer 1028 comprises an adhesion layer 1032 ofapproximately 80 nm of ITO, ICO, IWO or the like, a first metallic layer1034 a of approximately 46 nm of silver or silver alloy or the like, alayer 1034 b of approximately 80 nm of titanium oxide or the like, alayer 1036 a of approximately 85 nm of silicon oxide or the like, alayer 1034 c of approximately 188 nm of titanium oxide or the like, alayer 1036 b of approximately 48 nm of silicon oxide or the like, ametallic layer 1034 d of approximately 42 nm of silver or silver alloyor the like, and a layer 1036 c of approximately 77 nm of ITO, ICO orthe like. As shown in FIG. 17A, such a configuration provides atransmissivity of light through the reflective element with two peaktransmission bands, namely, a first spectral band having a peaktransmissivity of light having a wavelength of approximately 465 nm anda second spectral band having a peak transmissivity of light having awavelength of approximately 645 nm. The reflective element 1016 is thusspectrally tuned to substantially transmit both blue light, such aslight emitted from a blue light emitting diode display 1018 a, which mayemit light having a peak intensity of approximately 465 nm, and redlight, such as light emitted from a red light emitting diode display1018 b, which may emit light having a peak intensity of approximately645 nm. The transflective reflector and multiple stack ISI layer 1028provide an extra narrow band of transmissivity for each of the desiredspectral bands or ranges of wavelengths being emitted by the displays.Such a configuration thus may facilitate the implementation of differentcolored display elements, while providing enhanced reflectivity of lightoutside of the targeted spectral bands.

Referring now to FIG. 18, an electro-optic or electrochromic mirrorelement 1116 comprises a pair of substrates (a front substrate 1122 isshown in FIG. 18), with an electrochromic medium (not shown in FIG. 18)sandwiched therebetween. Electrochromic mirror element 1116 may comprisea reflective metallic layer or layers and transparent, at leastpartially conductive layers, such as discussed above, to provide atransflective mirror element. The electrochromic mirror element 1116includes one or more display elements, such as the three displayelements 1118 a, 1118 b, 1118 c shown in FIG. 18, positioned behind therear substrate and operable to emit or transmit light through thesubstrates and layers and electrochromic medium for viewing at the frontsubstrate 1122.

The electrochromic mirror element 1116 comprises at least two regions,such as the three regions 1116 a, 1116 b, 1116 c shown in FIG. 18. Acentral or principle viewing region 1116 a provides a respectivereflectivity and transmissivity, such as via layers or coatings asdescribed above. One or both side regions 1116 b, 1116 c also provide arespective reflectivity and transmissivity. In the illustratedembodiment, the display element or elements 1118 a, 1118 b, 1118 c arepositioned at the side or display regions 1116 b, 1116 c. The conductivemetallic and semiconductive non-metallic layers may be selected andadjusted so that the transmissivity in the side regions 1116 b, 1116 cmay be greater than the transmissivity in the central region 1116 a,while the reflectivity in the central region 1116 a may be greater thanthe reflectivity in the side or display regions 1116 b, 1116 c. Thepresent invention thus provides greater transmissivity in the displayregions to enhance viewing of the displays, while providing greaterreflectivity in the central or main region of the mirror element toprovide enhanced reflectivity in the principle viewing area.

In the illustrated embodiment, the transmissivity at the display regionsmay be approximately 25%, while the transmissivity in the central orprinciple viewing region may be approximately 20%. Likewise, thereflectivity in the central or principle viewing region may beapproximately 65%, while the reflectivity in the display regions may beapproximately 60%. Other reflective and transmissive characteristics maybe achieved without affecting the scope of the present invention.

The difference in the reflectivity and transmissivity between theregions is achieved by selecting different combinations of vapor sourceand masking of the regions to achieve the desired effect. For example,the thicknesses of different layers of the conductive metallic layer orlayers and of the transparent, at least partially conductive layers maybe selected or adjusted across the mirror element to achieve a desiredamount of transmissivity at the display regions, while maintainingsufficient reflectivity in these regions, and to achieve a desired oroptimum or maximum reflectivity at the central or principle viewing areaor region of the mirror element. For example, a reflective metalliccoating or layer may be thicker at the principle viewing region than atthe display region or regions, while a transparent layer or coating maybe thinner at the principle viewing region than at the display region orregions. Although shown as having display regions at the side regions ofthe mirror element, clearly displays and associated display regionsproviding enhanced transmissivity may be positioned elsewhere around themirror element, without affecting the scope of the present invention.

Therefore, the reflective element or mirror element of the presentinvention allows for a display element to be positioned behind thereflective layer and transmits light from the display element throughthe mirror element, while providing sufficient reflectivity across theentire mirror element and not requiring any windows or thinned areas ofreduced reflectivity in the display region. The present invention thusprovides a mirror assembly which may include multiple display-on-demandtype displays or display-on-need type displays, without adverselyaffecting the reflective nature of the reflective element. Furthermore,the transmissivity of the ISI or DOD stack or layer or the multiplestack ISI or DOD layers of the transflective reflector of the presentinvention may match or pinpoint the particular spectral bandcorresponding to the light emitted by the display element or device, inorder to provide improved transmission of the display information orlight through the stack (and thus through the reflective element), whileproviding a desired neutral reflectance over the entire surface of thereflector. The present invention thus may provide a reflective elementwhich has a transmissivity level of greater than at least approximately20 percent, more preferably at least approximately 30 percent, and mostpreferably at least approximately 50 percent, for light within aparticular narrow spectral band or range of wavelengths, while providingsubstantial reflectance of light outside of the particular, selectedspectral band or range of wavelengths. The reflective element of thepresent invention also provides for generally uniform thickness of theISI or DOD layers, since none of the layers have to be etched or maskedor reduced in thicknesses to allow for the display to transmittherethrough, thereby enhancing the manufacturing processing of thereflective element.

Optionally, the mirror assembly may include an illumination source forproviding illumination, such as near infrared and/or infraredillumination, within the cabin of the vehicle. For example, theillumination source may be directed toward the head of the driver of thevehicle (or the area or location where a typical driver's head wouldbe), and may be used in conjunction with a camera device or imagingdevice or the like. The imaging device or imaging system may comprise acabin monitoring system, such as a monitoring system utilizing theprinciples disclosed in U.S. Pat. Nos. 6,523,964; and 6,302,545, andU.S. patent applications, Ser. No. 10/372,873, filed Feb. 24, 2003, nowU.S. Pat. No. 6,802,617; Ser. No. 09/793,002, entitled VIDEO MIRRORSYSTEMS INCORPORATING AN ACCESSORY MODULE, filed Feb. 26, 2001, now U.S.Pat. No. 6.690.268; and Ser. No. 10/054,633, filed Jan. 22, 2002 byLynam et al. for VEHICULAR INTERIOR LED LIGHTING SYSTEM, now U.S. Pat.No. 7,195,381, which are hereby incorporated by reference herein.Optionally, the illumination source may be operable to illuminate thehead of the driver while the imaging device is operable to captureimages of the driver's head, such as for a video conferencing function,a driver alertness detection function (which may detect drowsinessissues, such as unorthodox head movement, nodding, glazed eyes, dilatingeyes or other characteristics which may be indicative of driver fatigueor reduced alertness), a seat occupancy detection function, an intrusiondetection function or any other desired functions. The illuminationsource or sources may comprise infrared or near infrared emittingsources, such as light emitting diodes (LEDs) or the like, to minimizethe affect on or visibility to the driver of the vehicle, such asdisclosed in U.S. Pat. Nos. 6,523,964; and 6,302,545, and U.S. patentapplication, Ser. No. 10/372,873, filed Feb. 24, 2003, now U.S. Pat. No.6,802,617, which are hereby incorporated herein by reference. Theimaging device thus may be capable of sensing infrared light, and may beparticularly sensitive to infrared or near infrared light, and maycomprise a CMOS imaging array or the like, such as disclosed in U.S.Pat. Nos. 5,550,677; 5,670,935; 5,760,962; 5,796,094 and 5,877,897,which are hereby incorporated herein by reference.

The interior rearview mirror assembly may provide the illuminationsource or sources at the bezel or chin or eyebrow of the mirrorassembly, or at a module or pod or the like associated with the mirrorassembly. Optionally, the mirror assembly may include the illuminationsource or sources within the mirror casing and behind the electrochromiccell of the mirror assembly, whereby the illumination source may emitnear infrared light or radiant energy and project the light through atransflective electrochromic element, which may have sufficienttransmissivity in the near infrared range of the spectrum, whilelimiting transmissivity of light in the visible range and providing adesired amount of untinted photopic reflectance, as discussed below. Theillumination source thus may be positioned behind the rear substrate ofthe electrochromic cell and may project the near infrared illuminationthrough both substrates of the reflective element or cell tosufficiently illuminate or bathe or flood the targeted area with nearinfrared illumination. The imaging device may also be positioned withinthe mirror casing and behind the transflective electrochromic element tocapture images of the scene illuminated by the near infraredillumination source or sources.

The transflective display on demand type reflective element preferablymaintains an untinted, high photopic reflectance of visible light, whilealso providing sufficient transmissivity of near infrared light orradiant energy (such as within the range of approximately 750 nm toapproximately 1100 nm). Preferably, the transflective display on demandelement provides at least approximately 30% transmissivity of nearinfrared light, preferably at least approximately 40%, more preferablyat least approximately 60% and most preferably at least approximately80% transmissivity of near infrared light. Typically, such near infraredtransmissivity may not be achieved utilizing reflective coatings orstacks of coatings that comprise or include a metallic layer, such as athin silver or silver alloy or aluminum or aluminum alloy layer or thelike. In such applications, the infrared or near infrared light emittedby the illumination source may reflect back into the cavity of themirror casing. The present invention overcomes this by providing aninfrared or near infrared transmitting stack of dielectric layers orcoatings which substantially transmit near infrared light while thetransflective element also provides high photopic reflectance of visiblelight. The transflective element may provide high photopic reflectanceand may meet the specifications set forth in SAE J964A, which is herebyincorporated herein by reference. Preferably, the transflective elementprovides greater than approximately 55%, more preferably greater thanapproximately 65% and most preferably greater than approximately 75%, ofsuch photopic reflectance.

Referring now to FIGS. 19-22, a transflective electrochromic element orcell 1216 includes a front substrate 1222 and a rear substrate 1224, andan illumination source 1244 and an imaging device 1246 at a rear orfourth surface of rear substrate 1224. A semi-conductive layer orcoating (such as ITO, tin oxide or the like) 1230 is deposited on theforward or third surface of rear substrate 1224, while a semi-conductivelayer 1226 (such as ITO, tin oxide or the like) is deposited on the rearor second surface of front substrate 1222. An electrochromic medium 1240and seal 1241 are provided or sandwiched between the semi-conductivelayers 1226, 1230, with an electrical connector 1248 positioned at leastpartially along at least one edge of each of the semi-conductive layers1226, 1230. The transflective cell 1216 further includes an infrared ornear infrared transmitting (IRT) stack or layers 1228, which, in theillustrated embodiment of FIG. 19, is positioned or stacked on the rearsurface of the rear substrate 1224. A protective cover or glass sheet1225 is adhered or secured to the rear surface of the IRT stack 1228,such as via an adhesive layer 1225 a, which preferably is an indexmatching adhesive that matches the index of the protective cover orsheet. The protective cover may comprise glass, or may comprise othertransparent or substantially clear materials, such as plastic,polycarbonate, acrylic or the like, without affecting the scope of thepresent invention.

IRT stack 1228 comprises multiple layers of dielectric layers orcoatings across the rear surface of rear substrate 1224 which functionas a cold mirror stack that allows near infrared and infrared light orradiant energy to pass therethrough while substantially reflectingvisible light. The IRT stack 1228 may comprise layers of titanium oxidealternating with silicon oxide layers. The titanium oxide layers providea higher refractive index while the silicon oxide layers provide a lowerrefractive index. The alternating combination of the lower and higherrefracting indices of alternating layers provides enhanced near infraredtransmissivity, while providing reflectivity of visible light.

In an exemplary embodiment, IRT stack 1228 comprises nineteen suchalternating layers having: a first titanium oxide layer approximately 72nm thick on the rear surface of substrate 1224, a first silicon oxidelayer approximately 32 nm thick on the first titanium oxide layer, asecond titanium oxide layer approximately 94 nm thick on the firstsilicon oxide layer, a second silicon oxide layer approximately 110 nmthick on the second titanium oxide layer, a third titanium oxide layerapproximately 64 nm thick on the second silicon oxide layer, a thirdsilicon oxide layer approximately 85 nm thick on the third titaniumoxide layer, a fourth titanium oxide layer approximately 62 nm thick onthe third silicon oxide layer, a fourth silicon oxide layerapproximately 128 nm thick on the fourth titanium oxide layer, a fifthtitanium oxide layer approximately 60 nm thick on the fourth siliconoxide layer, a fifth silicon oxide layer approximately 98 nm thick onthe fifth titanium oxide layer, a sixth titanium oxide layerapproximately 57 nm thick on the fifth silicon oxide layer, a sixthsilicon oxide layer approximately 94 nm thick on the sixth titaniumoxide layer, a seventh titanium oxide layer approximately 54 nm thick onthe sixth silicon oxide layer, a seventh silicon oxide layerapproximately 77 nm thick on the seventh titanium oxide layer, an eighthtitanium oxide layer approximately 36 nm thick on the seventh siliconoxide layer, an eighth silicon oxide layer approximately 83 nm thick onthe eighth titanium oxide layer, a ninth titanium oxide layerapproximately 58 nm thick on the eighth silicon oxide layer, a ninthsilicon oxide layer approximately 97 nm thick on the ninth titaniumoxide layer, and a tenth titanium oxide layer approximately 28 nm thickon the ninth silicon oxide layer. Clearly, other thicknesses andcombinations of layers may be implemented to achieve the desired levelsof transmissivity and reflectivity, without affecting the scope of thepresent invention. The transflective element thus provides a fourthsurface transflective mirror element, with multiple alternating layersof silicon oxide and titanium oxide to enhance the near infraredtransmissivity through the ITO layers and substrates.

The transmissivity percentage of such a substrate versus the lightwavelength is shown in FIG. 22. As can be seen in FIG. 22, the substrate1224 and IRT stack 1228 transmit more than 90% of near infrared light,while substantially not transmitting light in the visible range of thespectrum. The transflective element 1216 is thus spectrally tuned totransmit near infrared light emitted from illumination source 1244, andmay transmit the near infrared light from the scene back to the imagingsensor 1246. As can be seen in FIG. 22, the transmission is generallyconstant or flat for the desired wavelengths at an angle of incidence ofthe light source relative to the substrate between approximately 0degrees and approximately 50 degrees.

The arrangement shown in FIG. 19 may allow the mirror manufacturer topurchase the rear substrate sheet or material, which may be purchasedfrom a glass or substrate supplier or vendor with the front ITO layer orcoating and the cold mirror stack or IRT stack already applied theretoor deposited thereon. The ITO layers and alternating silicon oxide andtitanium oxide layers may be deposited on the respective surfaces orlayers via any known manner, such as vacuum deposition or the like, andsuch as disclosed in U.S. Pat. Nos. 5,668,663; 5,724,187; and 6,002,511,which are hereby incorporated herein by reference. This allows themirror manufacturer to select an appropriate rear substrate, dependingon the desired function or application of the mirror assembly, and toassemble the transflective element with the selected substrate. Themirror manufacturer may purchase the substrates, cut out the desiredshape for the mirror reflective element and glue or adhere or otherwisejoin the substrates (with coatings thereon) together (and sandwich theelectrochromic medium between the front and rear substrate) to form thedesired transflective element.

Prior to deposition, it is desirable/beneficial to clean the substrateusing a plasma source or an ion source, such as a linear ion source orthe like, which may result in enhanced adhesion of the thin films to thesubstrate. It is preferable that the substrate cleaning is accomplishedin one single pump down cycle of the vacuum coating process. Forexample, glass substrates can enter a vacuum chamber via a load-lock,and pass under a plasma source, such as a linear ion source or the like,where the surface-to-be-coated is activated/cleaned by exposure to aplasma and/or by ion bombardment or the like. The now plasmaactivated/ion-bombardment cleaned surface is then coated with an ITOlayer, followed by a metallic layer (such as silver), followed by an ITOlayer such as described herein. Optionally, and preferably, athree-sided target assembly is used, for example, one side may be alinear ion source, another side may be an ITO target, and the third sidemay be a silver target. The three-sided target assembly can, forexample, rotate (such as clockwise) to first ion clean the substrate,then rotate clockwise again to deposit ITO, then rotate clockwise againto deposit silver, and then rotate counterclockwise to deposit ITOagain. Suitable ion sources for such a cleaning purpose include AnodeLayer Sources (ALS), Kaufmann sources, gridded sources, non-griddedsources, RF sources and DC glow discharge sources and the like. The mostpreferred are the linear ion sources of the ALS type, such as areavailable from Veeco Instruments, Inc. of Colorado and Advanced Energy(AE) of Colorado.

Optionally, and desirably, the substrates 1222, 1224 may have a lowabsorption characteristic in the near infrared range or band of theenergy spectrum, whereby the substrates provide low absorption of nearinfrared radiant energy, such as at wavelengths of around 880 nm orthereabouts. The substrates thus may provide enhanced transmissivity ofsuch near infrared radiant energy through the transflectiveelectrochromic element or cell. Such low absorption characteristics maybe accomplished by selecting a material for the substrates that providesthe desired results. For example, the substrates may comprise aborosilicate material, such as the type that is commercially availablefrom Schott Glass Corp. under the name BOROFLOAT™, or may comprise aB270 material or SUPERWHITE™, also commercially available from SchottGlass Corp., or may comprise other materials, such as fused silica orquartz materials or the like, that may also or otherwise provide thedesired degree of low absorption of near infrared radiant energy. Othermaterials may be selected for the substrates of the transflectiveelectrochromic cell, without affecting the scope of the presentinvention.

Optionally, and with reference to FIG. 20, a transflective element 1216′may provide the IRT stack 1228′ on a front surface of the protectivecover or glass substrate or sheet 1225. In such an embodiment, the IRTstack 1228′ and cover 1225 are adhered or secured to the rear surface ofrear substrate 1224′ via the index matching adhesive 1225 a or the like.The arrangement shown in FIG. 20 allows the IRT stack to be manufacturedon a separate glass sheet or protective cover, whereby the mirrormanufacturer may purchase the front and rear substrates or sheets (withthe ITO layers already applied thereto or deposited thereon) and thethird glass sheet or protective cover with the IRT stack alreadydeposited thereon. The protective cover may comprise glass, or maycomprise other transparent or substantially clear materials, such asplastic, polycarbonate, acrylic or the like, without affecting the scopeof the present invention. The IRT stack and other components oftransflective element 1216′ may be substantially similar to the IRTstack and components of transflective element 1216 discussed above, suchthat a detailed discussion of these elements will not be repeatedherein.

Optionally, and with reference to FIG. 21, a transflective element 1216″may be substantially similar to transflective element 1216 of FIG. 19,discussed above, and may include a titanium oxide layer or coating 1227on the rear surface of the front substrate 1222′ and between the frontsubstrate 1222′ and the ITO layer or coating 1226′. The titanium oxidelayer 1227 may function to partially cancel out or compensate for anynear infrared reflectivity by the ITO layers of the cell or element tofurther enhance the performance of the transflective element.

Referring now to FIG. 23, a transflective electrochromic element or cell1316 includes a front substrate 1322 and a rear substrate 1324, and anillumination source 1344 and an imaging device 1346 at a rear or fourthsurface of rear substrate 1324. A semi-conductive layer or coating 1326(such as ITO, tin oxide or the like) is deposited on the rear or secondsurface of front substrate 1322. An IRT stack 1328 is applied to ordeposited on the front surface of rear substrate 1324, and asemi-conductive layer or coating 1330 (such as ITO, tin oxide or thelike) is deposited on IRT stack 1328. An electrochromic medium 1340 andseal 1341 are provided or sandwiched between the semi-conductive layers1326, 1330, with an electrical connector 1348 positioned at leastpartially along at least one edge of each of the semi-conductive layers1326, 1330.

Similar to IRT stack 1228 discussed above, IRT stack 1328 comprisesmultiple layers of dielectric layers or coatings. IRT stack or coldmirror stack 1328 is deposited on the front surface of rear substrate1324 and may comprise alternating layers of titanium oxide alternatingwith silicon oxide layers. The titanium oxide layers provide a higherrefractive index while the silicon oxides provide a lower refractiveindex. The combination of the lower and higher refractive indices of thealternating layers provides enhanced near infrared transmissivity, whileproviding reflectivity of visible light.

In an exemplary embodiment, IRT stack 1328 comprises nineteen suchalternating layers with a twentieth layer of ITO deposited on theoutermost IRT stack layer. For example, the IRT stack may comprise afirst titanium oxide layer approximately 53 nm thick on the rear surfaceof substrate 1324, a first silicon oxide layer approximately 57 nm thickon the first titanium oxide layer, a second titanium oxide layerapproximately 84 nm thick on the first silicon oxide layer, a secondsilicon oxide layer approximately 103 nm thick on the second titaniumoxide layer, a third titanium oxide layer approximately 58 nm thick onthe second silicon oxide layer, a third silicon oxide layerapproximately 96 nm thick on the third titanium oxide layer, a fourthtitanium oxide layer approximately 64 nm thick on the third siliconoxide layer, a fourth silicon oxide layer approximately 108 nm thick onthe fourth titanium oxide layer, a fifth titanium oxide layerapproximately 63 nm thick on the fourth silicon oxide layer, a fifthsilicon oxide layer approximately 93 nm thick on the fifth titaniumoxide layer, a sixth titanium oxide layer approximately 44 nm thick onthe fifth silicon oxide layer, a sixth silicon oxide layer approximately70 nm thick on the sixth titanium oxide layer, a seventh titanium oxidelayer approximately 37 nm thick on the sixth silicon oxide layer, aseventh silicon oxide layer approximately 61 nm thick on the seventhtitanium oxide layer, an eighth titanium oxide layer approximately 58 nmthick on the seventh silicon oxide layer, an eighth silicon oxide layerapproximately 102 nm thick on the eighth titanium oxide layer, a ninthtitanium oxide layer approximately 31 nm thick on the eighth siliconoxide layer, a ninth silicon oxide layer approximately 55 nm thick onthe ninth titanium oxide layer, and a tenth titanium oxide layerapproximately 49 nm thick on the ninth silicon oxide layer. Thesemi-conductive layer 1330 may comprise an ITO layer approximately 130nm thick. Clearly, other thicknesses and combinations of layers may beimplemented to achieve the desired levels of transmissivity andreflectivity, without affecting the scope of the present invention. Thetransflective element thus provides a third surface transflective mirrorelement, with multiple layers of silicon oxide and titanium oxide toenhance the near infrared transmissivity through the ITO layers andsubstrates.

The transmissivity percentage of such a substrate versus the lightwavelength is shown in FIG. 26. As can be seen in FIG. 26, such a rearsubstrate transmits more than approximately 90% of near infrared light,while substantially not transmitting light in the visible range of thespectrum. The transflective element 1316 is thus spectrally tuned totransmit near infrared light emitted from illumination source 1344, andmay transmit the near infrared light from the scene back to the imagingsensor 1346. As can be seen in FIG. 26, the transmission is generallyconstant or flat for the desired wavelengths at an angle of incidence ofthe light source relative to the substrate between approximately 0degrees and approximately 50 degrees.

The arrangement shown in FIG. 23 may allow the mirror manufacturer topurchase the rear substrate sheet or material, which may be purchasedfrom a glass or substrate supplier or vendor with the IRT or cold mirrorstack and the front ITO layer or coating already applied thereto ordeposited thereon. The ITO layers and silicon oxide and titanium oxidelayers may be deposited on the front surface or other layers via anyknown manner, such as vacuum deposition or the like, and such asdisclosed in U.S. Pat. Nos. 5,668,663; 5,724,187; and 6,002,511, whichare hereby incorporated herein by reference. This allows the mirrormanufacturer to select an appropriate rear substrate, depending on thedesired function or application of the mirror assembly, and to assemblethe transflective element with the selected substrate. The mirrormanufacturer may purchase the substrates, cut out the desired shape forthe mirror reflective element and glue, adhere or otherwise join thesubstrates (with coatings thereon) together (and sandwich theelectrochromic medium between the front and rear substrate) to form thedesired transflective element.

Optionally, and with reference to FIG. 24, a transflective element 1316′in accordance with the present invention may be substantially similar totransflective element 1316 discussed above, and may include a titaniumoxide layer or coating 1327 on the rear surface of the front substrate1322′ and between the front substrate 1322′ and the ITO layer or coating1326′. In an exemplary embodiment, the titanium oxide layer 1327 may beapproximately 250 nm thick, while the ITO layer 1326′ may beapproximately 130 nm thick, but other thicknesses may be implemented toachieve the desired result, without affecting the scope of the presentinvention. The titanium oxide layer 1327 may function to partiallycancel out or compensate for any near infrared reflectivity by the ITOlayers of the cell or element. This arrangement provides an enhancedsemi-conductive layer or coating on the rear surface of the frontsubstrate. A graphical depiction of the transmissivity of frontsubstrate 1322′ versus wavelength of light is shown in FIG. 27. In theillustrated embodiment, the peak transmissivity wavelength isapproximately 880 nm. Such a reflective element or cell thus may beparticularly suited for use with an imaging device or camera that has apeak sensitivity or response to light having a wavelength ofapproximately 880 nm.

Optionally, and with reference to FIG. 25, another transflective element1316″ in accordance with the present invention may be substantiallysimilar to transflective element 1316 of FIG. 23, discussed above, andmay include an enhanced semi-conductive layer on the rear surface of thefront substrate 1322″. The enhanced semi-conductive layer includes atitanium oxide layer or coating 1329 deposited on the rear surface ofthe front substrate 1322″, a silicon oxide layer 1327′ deposited ontitanium oxide layer 1329, and an ITO layer 1326″ deposited on siliconoxide layer 1327′. In an exemplary embodiment, the titanium oxide layer1329 may be approximately 109 nm thick, while the silicon oxide layer1327′ may be approximately 277 nm thick and the ITO layer 1326′ may beapproximately 130 nm thick. Other thicknesses may be implemented toachieve the desired result, without affecting the scope of the presentinvention. The titanium oxide layer 1329 and silicon oxide layer 1227′may function to partially cancel out or compensate for any near infraredreflectivity by the ITO layers of the cell or element to enhance thenear infrared transmissivity of the front substrate and semi-conductivelayers. A graphical depiction of the transmissivity of front substrate1322″ versus wavelengths of light is shown in FIG. 28. In theillustrated embodiment, the peak transmissivity wavelength isapproximately 880 nm. Such a reflective element or cell thus may beparticularly suited for use with an imaging device or camera that has apeak sensitivity or response to light having a wavelength ofapproximately 880 nm.

Optionally, and as shown in FIG. 29, a transflective element 1316″′ mayinclude the substrates 1322″, 1324′ and coatings or layers such asdescribed above with respect to transflective element 1316″ (FIG. 25),and may further include an anti-reflective (AR) stack or layers 1352 atthe rear surface of the rear substrate 1324′. The anti-reflective stackor layers 1352 may be selected to minimize the reflectance of light at adesired or targeted wavelength or range of wavelengths or spectral bandto enhance the overall transmissivity at the desired or targetedspectral band. For example, the anti-reflective stack 1352 may beselected to minimize the reflectance of near infrared radiant energy,such as radiant energy having a wavelength of approximately 880 nm orthereabouts, such that the transmission of such radiant energy may beenhanced. In an exemplary embodiment, anti-reflective stack or layers1352 comprises a layer of titanium oxide 1352 a deposited on or disposedat the rear surface of the rear substrate 1324 and a layer of siliconoxide 1352 b deposited on or disposed at the titanium oxide layer 1352a. In one embodiment, titanium oxide layer 1352 a may have a thicknessof approximately 25 nm, while silicon oxide layer 1352 b may have athickness of approximately 205 nm, such that the anti-reflective stackor layers 1352 reduces the reflectance of near infrared radiant energyhaving a wavelength of approximately 880 nm or thereabouts. Other layersor thicknesses may be selected to achieve other desired results, and maybe selected depending on the particular reflective element design andthe particular application of the reflective element, without affectingthe scope of the present invention. Such anti-reflective surfaces may beapplied to or disposed on the rearward surface of other mirror elementsof the present invention described herein.

Therefore, the present invention provides a transflective electrochromicelement or cell which may allow transmittance of near infrared lightthrough the substrates while providing a desired amount of untintedphotopic reflectance, and while also providing the desired degree ofconductivity at the conductive or semi-conductive layers. Thetransflective element may include multiple dielectric layers or coatingson one of the substrates or on a rear cover or glass sheet of thetransflective element. The dielectric layers cooperate to enhancetransmissivity of infrared or near infrared light through thesubstrates, while providing the desired level of untinted photopicreflectance. The transflective element thus may allow the mirrorassembly to include a near infrared light emitting diode or other nearinfrared emitting light source to be positioned behind the transflectiveelement and within the mirror casing, whereby the light source may emitor project near infrared light through the transflective element towardand into the cabin of the vehicle. The mirror assembly may also includean imaging device which may be positioned behind the transflectiveelement and may receive or capture images of the interior cabin of thevehicle which is covered by the near infrared light of the light source.

Optionally, and with reference to FIG. 30, it is envisioned that atransflective element 1416 in accordance with the present invention mayprovide high transmissivity of near infrared radiant energy, while alsoproviding high transmissivity of a particular wavelength or range ofwavelengths or spectral band or region of visible light, yet stillproviding high photopic reflectance of the other visible light andsufficient conductivity. Transflective element 1416 may be substantiallysimilar to the transflective elements 1316, 1316′, 1316″, discussedabove, but may include an infrared transmitting and display on demandstack 1428 (IRT-DOD stack) of alternating titanium oxide layers (or thelike) and silicon oxide layers (or the like) that may provide for hightransmissivity of near infrared radiant energy and high transmissivityof a desired visible light color, such as, for example, visible lighthaving a wavelength of approximately 430 nm (blue). Differentcombinations of alternating layers may be selected to provide sufficienttransmissivity of near infrared radiant energy and of other desiredspectral bands, without affecting the scope of the present invention.

The titanium oxide layers provide a higher refractive index while thesilicon oxides provide a lower refractive index. The combination of thelower and higher refractive indices of the alternating layers providesenhanced near infrared transmissivity, while providing high photopicreflectivity of most of the visible light, except the visible light inthe desired spectral region or having the desired or selected ortargeted wavelength. The transflective element thus may be used with anear infrared light emitting source 1444, which may be used inconjunction with an imaging source or camera 1446, and a display ondemand element 1450 that may emit light at the desired or selectedwavelength or color (such as, for example, blue light having awavelength of 430 nm) so that it is viewable through the reflectiveelement by a driver or occupant of the vehicle.

The other elements of the transflective element 1416 may besubstantially similar to the transflective elements 1316, 1316′, 1316″,discussed above, such that a detailed discussion of these elements willnot be repeated herein. The similar or common elements are shown in FIG.30 with similar reference numbers to those of FIG. 24, but with onehundred added to each number. In the illustrated embodiment of FIG. 29,the transflective element 1416 is shown with a titanium oxide (TiO₂)layer or coating 1427 on the rear surface of the front substrate 1422and between the front substrate 1422 and the ITO layer or coating 1426,similar to transflective element 1316′ of FIG. 24. However, othercoatings or layers may be deposited on or applied to the front substrateof the transflective element, such as, for example, the other layersdiscussed above, without affecting the scope of the present invention.

In an exemplary embodiment of the infrared transmitting and visiblelight transmitting transflective element 1416, the IRT-DOD stack 1428comprises nineteen such alternating layers with a twentieth layer of ITO1430 deposited on the outermost IRT-DOD stack or layers. For example,the IRT-DOD stack may comprise a first titanium oxide layerapproximately 50 nm thick on the surface of the substrate, a firstsilicon oxide layer approximately 83 nm thick on the first titaniumoxide layer, a second titanium oxide layer approximately 48 nm thick onthe first silicon oxide layer, a second silicon oxide layerapproximately 159 nm thick on the second titanium oxide layer, a thirdtitanium oxide layer approximately 50 nm thick on the second siliconoxide layer, a third silicon oxide layer approximately 97 nm thick onthe third titanium oxide layer, a fourth titanium oxide layerapproximately 61 nm thick on the third silicon oxide layer, a fourthsilicon oxide layer approximately 104 nm thick on the fourth titaniumoxide layer, a fifth titanium oxide layer approximately 59 nm thick onthe fourth silicon oxide layer, a fifth silicon oxide layerapproximately 84 nm thick on the fifth titanium oxide layer, a sixthtitanium oxide layer approximately 35 nm thick on the fifth siliconoxide layer, a sixth silicon oxide layer approximately 65 nm thick onthe sixth titanium oxide layer, a seventh titanium oxide layerapproximately 46 nm thick on the sixth silicon oxide layer, a seventhsilicon oxide layer approximately 76 nm thick on the seventh titaniumoxide layer, an eighth titanium oxide layer approximately 48 nm thick onthe seventh silicon oxide layer, an eighth silicon oxide layerapproximately 175 nm thick on the eighth titanium oxide layer, a ninthtitanium oxide layer approximately 19 nm thick on the eighth siliconoxide layer, a ninth silicon oxide layer approximately 61 nm thick onthe ninth titanium oxide layer, and a tenth titanium oxide layerapproximately 37 nm thick on the ninth silicon oxide layer. Thesemi-conductive layer 1430 may comprise an ITO layer or the like ofapproximately 130 nm thick. Clearly, other thicknesses and combinationsof layers may be implemented to achieve the desired levels oftransmissivity and reflectivity, such as high transmissivity of othercolors or spectral regions of the spectrum, without affecting the scopeof the present invention. The transflective element thus provides athird surface transflective mirror element, with multiple layers ofsilicon oxide and titanium oxide to enhance the near infraredtransmissivity and particular visible light wavelength or wavelengthsthrough the ITO layers and substrates.

The transmissivity percentage of such a substrate versus the lightwavelength is shown in FIG. 31. As can be seen in FIG. 31, such asubstrate transmits more than approximately 90% of near infrared light,while substantially reflecting or not transmitting light in the visiblerange of the spectrum, except for light having a wavelength ofapproximately 430 nm, which is also highly transmitted (such as atgreater than approximately 90% transmissivity) by the substrate andalternating layers of the IRT-DOD stack. The transflective element isthus spectrally tuned to transmit near infrared light that may beemitted from an illumination source 1444, and may transmit the nearinfrared light from the scene back to an imaging sensor 1446. Thetransflective element may also transmit light having a desired ortargeted wavelength to allow for a colored display element orillumination source or indicator 1450 to be viewed through thetransflective element.

Although shown and described as being implemented on a third surface ofan electrochromic mirror element, it is envisioned that the layers orstacks of the present invention may be implemented at a fourth surfaceof the electrochromic reflective element, such as for a fourth surfacereflective element, without affecting the scope of the presentinvention. In such an application, a radiant energy emitting device orelement and/or an imaging sensor may be positioned rearward of the stackor layers for emitting or receiving radiant energy through thereflective element. Also, a protective layer or cover may be providedover the rearwardmost layer of the alternating layers and over or aroundthe display element or sensor to protect the layers at the rear of thereflective element.

Also, although shown and described as being implemented in anelectrochromic reflective element or cell, the alternating layers orstacks of the present invention may be implemented at a rear surface(second surface) of a prismatic reflective element, without affectingthe scope of the present invention. For example, and with reference toFIG. 32, a prismatic reflective element 1516 may comprise a prismatic orwedge-shaped substrate 1522 having a forward or outwardly facing surface1522 a and a rearward surface 1522 b opposite the forward surface 1522a. Prismatic reflective element 1522 includes alternating layers or astack 1528 disposed at rear surface 1522 b of prismatic substrate 1522.As shown in FIG. 32, a protective layer or coating 1525 may be appliedover the stack 1528. The layers of stack 1528 may comprise alternatinglayers of metallic and non-metallic layers or coatings, such as layersor stacks similar to the ISI stacks or DOD stacks or IRT stacks orIRT-DOD stacks of the present invention, as discussed above, dependingon the particular application of the prismatic reflective element. Theparticular materials and thicknesses of the layers may be selected toprovide the desired transmissivity of a particular selected spectralband or bands of radiant energy through the prismatic reflectiveelement, while providing sufficient reflectivity of other spectral bandsof radiant energy.

Prismatic reflective element 1516 may include a display element orradiant energy emitting device or illumination source 1544 positioned ata rear surface of the rearward most layer of stack 1528 and operable toemit radiant energy, such as visible light, near infrared radiant energyor infrared radiant energy through stack 1528 and prismatic substrate1522. The thicknesses and materials of the layers of stack 1528 may beselected to provide enhanced transmissivity of radiant energy or lightwithin a particular spectral band through stack 1528 and prismaticsubstrate 1522, while providing sufficient reflectivity of light havingwavelengths outside of the selected particular spectral band. Theparticular spectral band may be selected to match the spectral band oflight or radiant energy emitted by radiant energy emitting device 1544,such as in the manners discussed above. Optionally, the prismaticreflective element may include an imaging sensor or the like, such asdiscussed above with respect to electrochromic reflective element 1316or 1416, without affecting the scope of the present invention.

The radiant energy emitting element or display element thus may beviewable through the prismatic substrate without requiring windows orthe like formed in the reflective layer at the rear of the prismaticsubstrate. The layers or stacks of the present invention thus mayprovide an improved display on demand or display on need type of displayelement for a prismatic reflective element. Although shown as aprismatic or wedge-shaped substrate, the substrate may comprise asubstantially flat substrate or may comprise a curved substrate havingone or more curved surfaces, without affecting the scope of the presentinvention.

Although described as being implemented with interior rearview mirrorassemblies, it is further envisioned that the layers or stacks of thepresent invention may be implemented with reflective elements forexterior rearview mirror assemblies, such as exterior electrochromicrearview mirror assemblies or other exterior rearview mirror assemblies,such as exterior rearview mirror assemblies having a single flatsubstrate or having a curved outer surface or substrate or the like,without affecting the scope of the present invention. For example, anexterior reflective element may have a stack of alternating layers (suchas the types discussed above) that may have enhanced transmissivity ofvisible light that has a spectral band that matches a color output of aturn signal indicator or other indicator or light emitting devicepositioned behind the reflective element, such as within the casing ofthe exterior rearview mirror assembly. The indicator may thus beviewable through the reflective element when the indicator is activated,while the reflective element substantially reflects other light over itsentire viewing surface. The exterior rearview mirror assembly of thepresent invention thus may provide an indicator for viewing through thereflective element without requiring a window to be formed in thereflective layer or surface of the exterior reflective element. Thepresent invention thus may provide a display on demand or display onneed type of display to an exterior rearview mirror assembly.Optionally, the alternating layers may comprise an IRT stack or IRT-DODstack, such as described above, and the exterior rearview mirrorassembly may include an infrared or near infrared emitting element, andmay include an imaging sensor or device or camera, such as for a side orrearward imaging system of the vehicle (such as for a viewing systemsuch as the types disclosed in U.S. Pat. Nos. 5,550,677; 5,670,935 and6,201,642, which are hereby incorporated herein by reference, or such asfor a lane change assist system or side objection detection system orthe like, such as the types disclosed in U.S. patent applications, Ser.No. 10/209,173, filed Jul. 31, 2002 by Schofield for AUTOMOTIVE LANECHANGE AID, now U.S. Pat. No. 6,882,287, Ser. No. 10/427,051, filed Apr.30, 2003 by Pawlicki et al. for OBJECT DETECTION SYSTEM FOR VEHICLE, nowU.S. Pat. No. 7,038,577, which are hereby incorporated herein byreference). The near infrared emitting element or elements may bepositioned within the exterior rearview mirror assembly and behind thereflective element and may provide illumination at the side of thevehicle without distracting or adversely affecting the view or vision ofdrivers of other vehicles at the side of the subject vehicle.

The present invention thus provides mirror reflective elements thatprovide substantial visible reflectivity, and that may providesubstantial transmissivity of near infrared light, and that may also orotherwise provide substantial transmissivity of visible light within aselected spectral band or region or range of wavelengths. The mirrorreflective elements of the present invention thus may be spectrallytuned for the desired application, while still providing the desireddegree of photopic reflectivity and the desired conductivity on theconductive or semi-conductive layers, such that the electrochromicmedium of the mirror cell colors or darkens in a desired manner.

The electrical connectors for the transflective electrochromic cells orelements of the present invention may comprise clip connectors,electrical busbars or the like, such as disclosed in U.S. Pat. Nos.5,066,112 and 6,449,082, which are hereby incorporated herein byreference. Although shown as having the substrates and connectorsoffset, clearly the transflective element may comprise a flush element,such as described in U.S. Pat. No. 5,066,112, or such as described inU.S. provisional applications, Ser. No. 60/490,111, filed Jul. 25, 2003by McCabe et al. for FLUSH ELECTROCHROMIC CELL (Attorney Docket DON01P-1102); and Ser. No. 60/423,903, filed Nov. 5, 2002 by McCabe for ONESIDED FLUSH ELECTROCHROMIC CELL (Attorney Docket DON01 P-1032), whichare all hereby incorporated herein by reference. Such a flushtransflective element may facilitate a no-bezel or bezelless or lowbezel mirror casing or assembly, with minimal or no offset between thesubstrates of the mirror assembly.

As discussed above, the mirror assembly of the present invention mayinclude a display for providing information for viewing by the driver ofthe vehicle on the reflective element so that the driver can easily seethe display. In order to maintain easy viewing of the display, it isdesirable to adjust the display intensity in response to ambient lightlevels (in order to avoid washout during daytime driving conditions andglare during nighttime driving conditions) and in response to the degreeof transmissivity of the electrochromic reflective element. For example,in low lighting conditions, such as during the nighttime, the intensityof the display may be dimmed to avoid glare, while in higher lightingconditions, such as during the daytime, the intensity of the display maybe increased to provide sufficient visibility of the display to thedriver of the vehicle. The mirror assembly may include light sensors forsensing the ambient light in the cabin of the vehicle or at the mirrorassembly and may include a control which is operable to automaticallyadjust the display intensity and/or the transmissivity of theelectrochromic medium in response to the ambient light sensors.

Further, automatic dimming circuitry used in electrochromic mirrorassemblies utilizing the reflective elements of the current inventionmay utilize one or more (typically two) photo sensors to detect glaringand/or ambient lighting. For example, a silicon photo sensor such as aTSL235R Light-to-Frequency converter (available from Texas AdvancedOptoelectronic Solutions Inc. of Plano, Tex.) can be used as such photosensors. Such light-to-frequency converters comprise the combination ofa silicon photodiode and a current-to-frequency converter on a singlemonolithic CMOS integrated circuit.

The mirror assembly or assemblies of the present invention may alsoinclude or house a plurality of electrical or electronic devices, suchas antennas, including global positioning system (GPS) or cellular phoneantennas, such as disclosed in U.S. Pat. No. 5,971,552, a communicationmodule, such as disclosed in U.S. Pat. No. 5,798,688, displays, such asshown in U.S. Pat. Nos. 5,530,240 and 6,329,925, blind spot detectionsystems, such as disclosed in U.S. Pat. Nos. 5,929,786 or 5,786,772,transmitters and/or receivers, such as garage door openers, a digitalnetwork, such as described in U.S. Pat. No. 5,798,575, a high/low headlamp controller, such as disclosed in U.S. Pat. No. 5,715,093, a memorymirror system, such as disclosed in U.S. Pat. No. 5,796,176, ahands-free phone attachment, a video device for internal cabinsurveillance and/or video telephone function, such as disclosed in U.S.Pat. Nos. 5,760,962 and 5,877,897, a remote keyless entry receiver, maplights, such as disclosed in U.S. Pat. Nos. 5,938,321; 5,813,745;5,820,245; 5,673,994; 5,649,756; or 5,178,448, microphones, such asdisclosed in U.S. Pat. Nos. 6,243,003 and 6,278,377, speakers, acompass, such as disclosed in U.S. Pat. No. 5,924,212 or U.S. patentapplication, Ser. No. 10/456,599, filed Jun. 6, 2003 by Weller et al.for INTERIOR REARVIEW MIRROR SYSTEM WITH COMPASS, now U.S. Pat. No.7,004,593, seat occupancy detector, a trip computer, an ONSTAR® systemor the like (with all of the above-referenced patents and applicationsbeing commonly assigned to Donnelly Corporation, and with thedisclosures of the referenced patents and applications being herebyincorporated herein by reference in their entireties).

The mirror assembly and/or reflective element of the present inventionmay include a printed circuit board (PCB) which may be attached to itsrear surface (e.g. the fourth surface) by, for example, a suitableadhesive or the like. An example of such an arrangement is disclosed incommonly assigned U.S. Pat. No. 5,820,245, which is incorporated in itsentirety by reference herein. The PCB optionally may include glaresensing and ambient photo sensors and electrochromic circuitry thatautomatically dims the reflectivity of the electrochromic mirror elementwhen glare conditions are detected, such as at nighttime or the like.Alternately, the PCB may be snap connected, by a clip or otherwiseattached, to a plastic plate that itself is adhered to theelectrochromic element.

The printed circuit board may include electronic or electrical circuitryfor actuating the variable reflectance of the reflective element and foroperating other electrical or electronic functions supported in therearview mirror assembly. The circuit board may support, for example,light emitting diodes (LEDs) for illuminating indicia on displayelements provided on the chin of the bezel of the mirror assembly ordisplay devices provided on the reflective element, or map or dash boardlights or the like. The circuit board may be independently supportedfrom the reflective element or in the casing or may be mounted to thereflective element's rear or fourth surface on a separate plate or maybe directly adhered to the rear surface by a suitable adhesive.Reference is made to U.S. Pat. Nos. 5,671,996 and 5,820,245, thedisclosures of which are hereby incorporated herein by reference intheir entireties.

Therefore, the present invention provides a reflective element whichprovides a combination of substantially transparent, conductive orsemi-conductive layers and substantially reflective, conductive metalliclayer or layers on one of the surfaces of the reflective element, suchas the inward surface (or third surface) of a second substrate of anelectrochromic reflective element or a rear surface (or fourth surface)of an electrochromic reflective element or a rear surface of a prismaticreflective element or the like. The reflective element of the presentinvention provides enhanced manufacturing processing of the reflectiveelement, since the thicknesses of the layers and tolerances associatedtherewith are sufficiently large enough to be sputter coated orotherwise deposited via a low cost process. The reflective element ofthe present invention also provides for a reflective and transmissiveelement which allows transmission of display information through thereflective element, while still providing sufficient reflectance overthe entire surface of the reflective element, even in the display area.Accordingly, multiple displays may be positioned on, at or around thereflective element, without loss of reflectivity of the element. Thematerials and thicknesses of the layers of the reflective element may beselected to spectrally tune the reflective element to allow transmissionof one or more particular spectral bands or range of wavelengths, inorder to tune the reflective element for use with a particular spectralband of light being emitted by a particular display. The materials andthicknesses of the layers may also be selected to spectrally tune thereflective element to enhance transmissivity of near infrared radiantenergy. Also, the thicknesses of one or more layers may be varied acrossthe mirror element to provide regions or areas of increasedtransmissivity for a display, while maintaining a desired level ofreflectivity at the principle viewing area of the mirror element. Themirror element may comprise an electrochromic element or a prismaticelement and may be implemented at an interior rearview mirror assemblyor an exterior rearview mirror assembly. Optionally, the mirror elementmay comprise a substantially flat element or may comprise a curvedelement, such as a convex element or aspheric element or the like.

Changes and modifications in the specifically described embodiments canbe carried out without departing from the principles of the invention,which is intended to be limited only by the scope of the appendedclaims, as interpreted according to the principles of patent law.

1. A mirror assembly for a vehicle, said mirror assembly comprising: amirror element comprising at least one substrate having a forwardsurface facing towards a viewer of the mirror assembly and a rearwardsurface facing away from a viewer of the mirror assembly, said mirrorelement comprising at least one substantially reflective metallic layersandwiched between a respective pair of substantially transparentnon-metallic layers, each of said substantially transparent non-metalliclayers and said substantially reflective metallic layer having aselected refractive index and a selected physical thickness such thatsaid mirror element is selectively spectrally tuned to substantiallytransmit at least one preselected spectral band of radiant energytherethrough while substantially reflecting other radiant energy,wherein said at least one preselected spectral band comprises apreselected band of near infrared radiant energy; a radiant energyemitting element at or near said rearward surface of said at least onesubstrate, said radiant energy emitting element being operable to emitradiant energy towards said rearward surface and through said mirrorelement, said radiant energy emitting element being operable to emitnear infrared radiant energy with a peak intensity within saidpreselected spectral band of near infrared radiant energy; an imagingsensor at or near said rearward surface, said imaging sensor beingsensitive to near infrared radiant energy in the range of approximately750 nm to approximately 1100 nm.
 2. A mirror assembly for a vehicle,said mirror assembly comprising: a mirror element comprising at leastone substrate having a forward surface facing towards a viewer of themirror assembly and a rearward surface facing away from a viewer of themirror assembly, said mirror element comprising at least onesubstantially reflective metallic layer sandwiched between a respectivepair of substantially transparent non-metallic layers, each of saidsubstantially transparent non-metallic layers and said substantiallyreflective metallic layer having a selected refractive index and aselected physical thickness such that said mirror element is selectivelyspectrally tuned to substantially transmit at least one preselectedspectral band of radiant energy therethrough while substantiallyreflecting other radiant energy; and a radiant energy emitting elementat or near said rearward surface of said at least one substrate, saidradiant energy emitting element being operable to emit radiant energytowards said rearward surface and through said mirror element, saidradiant energy emitting element being operable to emit radiant energywith a peak intensity within said at least one preselected spectralband, wherein said at least one preselected spectral band comprisesfirst and second preselected bands of radiant energy, said radiantenergy emitting element comprises first and second radiant energyemitting elements, said first radiant energy emitting element beingoperable to emit radiant energy with a peak intensity within said firstpreselected spectral band of radiant energy and said second radiantenergy emitting element being operable to emit radiant energy with apeak intensity within said second preselected spectral band of radiantenergy.
 3. The mirror assembly of claim 2, wherein said first and secondpreselected bands of radiant energy comprise first and secondpreselected bands of visible light, said first band being a differentband than said second band.
 4. The mirror assembly of claim 2, whereinsaid first preselected band of radiant energy comprises a band of nearinfrared radiant energy and said second preselected band of radiantenergy comprises a band of visible light.
 5. A mirror assembly for avehicle, said mirror assembly comprising: a mirror element comprising atleast one substrate having a forward surface facing towards a viewer ofthe mirror assembly and a rearward surface facing away from a viewer ofthe mirror assembly, said mirror element comprising at least onesubstantially reflective metallic layer sandwiched between a respectivepair of substantially transparent non-metallic layers, each of saidsubstantially transparent non-metallic layers and said substantiallyreflective metallic layer having a selected refractive index and aselected physical thickness such that said mirror element is selectivelyspectrally tuned to substantially transmit at least one preselectedspectral band of radiant energy therethrough while substantiallyreflecting other radiant energy; and a radiant energy emitting elementat or near said rearward surface of said at least one substrate, saidradiant energy emitting element being operable to emit radiant energytowards said rearward surface and through said mirror element, saidradiant energy emitting element being operable to emit radiant energywith a peak intensity within said at least one preselected spectralband, wherein said mirror element comprises at least two substantiallyreflective metallic layers, each of said at least two substantiallyreflective metallic conductive layers being sandwiched between arespective pair of substantially transparent non-metallic layers.
 6. Amirror assembly for a vehicle, said mirror assembly comprising: a mirrorelement comprising at least one substrate having a forward surfacefacing towards a viewer of the mirror assembly and a rearward surfacefacing away from a viewer of the mirror assembly, said mirror elementcomprising at least one substantially reflective metallic layersandwiched between a respective pair of substantially transparentnon-metallic layers, each of said substantially transparent non-metalliclayers and said substantially reflective metallic layer having aselected refractive index and a selected physical thickness such thatsaid mirror element is selectively spectrally tuned to substantiallytransmit at least one preselected spectral band of radiant energytherethrough while substantially reflecting other radiant energy;wherein said at least one substrate comprises first and secondsubstrates, said first substrate having said forward surface and asecond surface opposite said forward surface, said second substratehaving said rearward surface and a third surface opposite said rearwardsurface, said first and second substrates being arranged so that saidsecond surface opposes said third surface, said mirror elementcomprising an electrochromic medium disposed between said first andsecond substrates; and a radiant energy emitting element at or near saidrearward surface of said at least one substrate, said radiant energyemitting element being operable to emit radiant energy towards saidrearward surface and through said mirror element, said radiant energyemitting element being operable to emit radiant energy with a peakintensity within said at least one preselected spectral band.
 7. Themirror assembly of claim 6 including an anti-reflective stack of layersat said rearward surface, said anti-reflective stack being spectrallytuned to minimize reflectance of radiant energy at said preselectedspectral band.
 8. The mirror assembly of claim 6, wherein saidsubstantially transparent non-metallic layers and said substantiallyreflective metallic layer are disposed between said electrochromicmedium and said third surface, wherein said mirror element comprises atransflective reflector at said third surface.
 9. The mirror assembly ofclaim 6, wherein said substantially transparent non-metallic layers andsaid substantially reflective metallic layer are disposed at saidrearward surface of said second substrate, wherein said mirror elementcomprises a fourth surface reflective element.
 10. The mirror assemblyof claim 6, wherein said substantially transparent non-metallic layerscomprise substantially transparent semi-conductive non-metallic layersand said substantially reflective metallic layer comprises asubstantially reflective conductive metallic layer.
 11. The mirrorassembly of claim 6, wherein said at least one preselected spectral bandcomprises a preselected band of visible light, said radiant energyemitting element being operable to emit visible radiant energy with apeak intensity within said preselected spectral band of visible light.12. The mirror assembly of claim 6, wherein said at least onepreselected spectral band comprises a preselected band of near infraredradiant energy, said radiant energy emitting element being operable toemit near infrared radiant energy, with a peak intensity within saidpreselected spectral band of near infrared radiant energy.
 13. Themirror assembly of claim 10, wherein said substantially transparentsemi-conductive non-metallic layers and said substantially reflectiveconductive metallic layer conduct electricity to darken or color saidelectrochromic medium in response to a voltage being applied to saidlayers.
 14. The mirror assembly of claim 5, wherein said at least onesubstrate comprises a single substrate, said substantially transparentnon-metallic layers and said substantially reflective metallic layerbeing disposed at said rearward surface of said single substrate. 15.The mirror assembly of claim 14, wherein said single substrate comprisesa prismatic substrate.
 16. A mirror assembly for a vehicle, said mirrorassembly comprising: a mirror element comprising at least one substratehaving a forward surface facing towards a viewer of the mirror assemblyand a rearward surface facing away from a viewer of the mirror assembly,said mirror element comprising at least one substantially reflectivemetallic layer sandwiched between a respective pair of substantiallytransparent non-metallic layers, each of said substantially transparentnon-metallic layers and said substantially reflective metallic layerhaving a selected refractive index and a selected physical thicknesssuch that said mirror element is selectively spectrally tuned tosubstantially transmit at least one preselected spectral band of radiantenergy therethrough while substantially reflecting other radiant energy;at least one adhesion enhancement and passivation layer disposed betweensaid reflective metallic layer and at least one of said transparentnon-metallic layers to increase the corrosion resistance of saidreflective metallic layer and to enhance the adhesion and the mechanicalstability of said reflective metallic layer; and a radiant energyemitting element at or near said rearward surface of said at least onesubstrate, said radiant energy emitting element being operable to emitradiant energy towards said rearward surface and through said mirrorelement, said radiant energy emitting element being operable to emitradiant energy with a peak intensity within said at least onepreselected spectral band.
 17. An electrochromic mirror assembly for avehicle, said mirror assembly comprising: an electrochromic mirrorelement comprising a first substrate having first and second surfacesand a second substrate having third and fourth surfaces, said first andsecond substrates being arranged so that said second surface opposessaid third surface with an electrochromic medium disposed therebetween;said third surface of said second substrate comprising a transflectivereflector comprising a first substantially transparent semi-conductivenon-metallic layer contacting the electrochromic medium, a secondsubstantially transparent semi-conductive non-metallic layer, and asubstantially reflecting metallic conductive layer sandwiched betweensaid first and second substantially transparent semi-conductivenon-metallic layers, wherein when said mirror element is viewed fromoutside said first surface, said mirror element is substantiallyspectrally untinted when no voltage is applied across saidelectrochromic medium, said mirror element being at least partiallyspectrally selective in transmission and exhibiting a spectrallyselective transmission characteristic, said spectrally selectivetransmission characteristic being established by the refractive indicesand physical thicknesses of said first and second substantiallytransparent semi-conductive non-metallic layers and said substantiallyreflective metallic conductive layer; and a light emitting elementdisposed at said fourth surface of said second substrate and operable toemit light having an emitted spectral characteristic through said mirrorelement, wherein said transflective reflector is configured to exhibit aspectrally selective transmission characteristic so as to substantiallytransmit light having a spectral band in regions at or near said emittedspectral characteristic and to substantially reflect other light havinga spectral band outside of said regions, wherein said transflectivereflector provides at least 15 percent transmissivity of light at ornear said emitted spectral characteristic and provides at least 60percent photopic reflectance of other light.
 18. An electrochromicmirror assembly for a vehicle, said mirror assembly comprising: anelectrochromic mirror element comprising a first substrate having firstand second surfaces and a second substrate having third and fourthsurfaces, said first and second substrates being arranged so that saidsecond surface opposes said third surface with an electrochromic mediumdisposed therebetween; said third surface of said second substratecomprising a transflective reflector, wherein said transflectivereflector comprises at least two substantially reflective metallicconductive layers, each of said at least two substantially reflectivemetallic conductive layers being sandwiched between a respective pair ofsubstantially transparent semi-conductive non-metallic layers disposedbetween said electrochromic medium and said second substrate, whereinwhen said mirror element is viewed from outside said first surface, saidmirror element is substantially spectrally untinted when no voltage isapplied across said electrochromic medium, said mirror element being atleast partially spectrally selective in transmission and exhibiting aspectrally selective transmission characteristic, said spectrallyselective transmission characteristic being established by therefractive indices and physical thicknesses of said substantiallytransparent semi-conductive non-metallic layers and said substantiallyreflective metallic conductive layer; and a light emitting elementdisposed at said fourth surface of said second substrate and operable toemit light having an emitted spectral characteristic through said mirrorelement, wherein said transflective reflector is configured to exhibit aspectrally selective transmission characteristic so as to substantiallytransmit light having a spectral band in regions at or near said emittedspectral characteristic and to substantially reflect other light havinga spectral band outside of said regions.
 19. The electrochromic mirrorassembly of claim 18, wherein said transflective reflector provides atleast 20 percent transmissivity of light at or near said emittedspectral characteristic.
 20. The electrochromic mirror assembly of claim18, wherein said transflective reflector provides at least 10 percenttransmissivity of light at or near said emitted spectral characteristic.21. The electrochromic mirror assembly of claim 20, wherein saidtransflective reflector provides at least 60 percent photopicreflectance of other light.
 22. The electrochromic mirror assembly ofclaim 20, wherein said transflective reflector provides at least 70percent photopic reflectance of other light.
 23. The electrochromicmirror assembly of claim 20, wherein said transflective reflectorprovides at least 80 percent photopic reflectance of other light. 24.The electrochromic mirror assembly of claim 18, wherein saidtransflective reflector provides at least 30 percent transmissivity oflight at or near said emitted spectral characteristic and provides atleast 60 percent photopic reflectance of other light.
 25. Theelectrochromic mirror assembly of claim 17, wherein said secondsubstantially transparent semi-conductive non-metallic layer contactssaid third surface of said second substrate.
 26. The electrochromicmirror assembly of claim 18, wherein said transflective reflectorsubstantially transmits light having said spectral band in the nearinfrared region of the spectrum, said light emitting element beingoperable to emit near infrared light through said transflectivereflector.
 27. The electrochromic mirror assembly of claim 26 includingan imaging sensor at said fourth surface that is operable to sense nearinfrared light.
 28. The electrochromic mirror assembly of claim 26,wherein said transflective reflector substantially transmits lighthaving a second spectral band in a visible region of the spectrum, saidmirror assembly including a second light emitting element at said fourthsurface, said second light emitting element being operable to emit lightthat has a peak intensity at or near said second spectral band throughsaid transflective reflector.
 29. The electrochromic mirror assembly ofclaim 18, wherein said transflective reflector substantially transmitslight having said spectral band at a first visible region of thespectrum.
 30. The electrochromic mirror assembly of claim 29, whereinsaid transflective reflector substantially transmits light having asecond spectral band in a second visible region of the spectrum, saidmirror assembly including a second light emitting element at said fourthsurface, said second light emitting element being operable to emit lightthat has a peak intensity at or near said second spectral band throughsaid transflective reflector.
 31. An electrochromic mirror assembly fora vehicle, said mirror assembly comprising: an electrochromic mirrorelement comprising a first substrate having first and second surfacesand a second substrate having third and fourth surfaces, said first andsecond substrates being arranged so that said second surface opposessaid third surface with an electrochromic medium disposed therebetween;said third surface of said second substrate comprising at least oneconductive metallic layer and at least one transparent, at leastpartially conductive layer. wherein said layers define first and secondregions of said transflective reflector, said first region having afirst reflectivity and a first transmissivity and said second regionhaving a second reflectivity and a second transmissivity, said secondtransmissivity being greater than said first transmissivity, said firstreflectivity being greater than said second reflectivity, wherein saidfirst reflectivity comprises at least approximately 60 percent; and adisplay element positioned at said fourth surface of said secondsubstrate and operable to transmit light through said second region ofsaid transflective reflector.
 32. The electrochromic mirror assembly ofclaim 31, wherein said first region comprises a generally central regionof said electrochromic mirror element and said second region comprisesat least one side region of said electrochromic mirror element.
 33. Anelectrochromic mirror assembly for a vehicle, said mirror assemblycomprising: an electrochromic mirror element comprising a firstsubstrate having first and second surfaces and a second substrate havingthird and fourth surfaces, said first and second substrates beingarranged so that said second surface opposes said third surface with anelectrochromic medium disposed therebetween; said third surface of saidsecond substrate comprising at least one conductive metallic layer andat least one transparent, at least partially conductive layer, whereinsaid layers define first and second regions of said transflectivereflector, said first region having a first reflectivity and a firsttransmissivity and said second region having a second reflectivity and asecond transmissivity, said second transmissivity being greater thansaid first transmissivity, wherein said transflective reflectorcomprises a first substantially transparent semi-conductive layercontacting the electrochromic medium, a second substantially transparentsemi-conductive layer, and a substantially reflecting metallicconductive layer sandwiched between said first and second substantiallytransparent semi-conductive layers; and a display element positioned atsaid fourth surface of said second substrate and operable to transmitlight through said second region of said transflective reflector. 34.The electrochromic mirror assembly of claim 33, wherein said firstreflectivity is greater than said second reflectivity.
 35. Theelectrochromic mirror assembly of claim 34, wherein a thickness of atleast one of said layers is varied between said first and secondregions.
 36. The electrochromic mirror assembly of claim 35, whereineach of said first and second transparent semi-conductive layers andsaid substantially reflective metallic conductive layer of said secondregion have a selected refractive index and a selected physicalthickness such that said transflective reflector is selectivelyspectrally tuned to substantially transmit at least one preselectedspectral band of light therethrough while substantially reflecting otherlight, said display element being operable to transmit light with a peakintensity within said preselected spectral band through said secondregion of said transflective reflector.
 37. A mirror assembly for avehicle, said mirror assembly comprising: a mirror element comprising asubstrate having a forward surface facing towards a viewer of the mirrorassembly and a rearward surface facing away from a viewer of the mirrorassembly, said mirror element comprising at least one substantiallyreflective metallic layer sandwiched between a respective pair ofsubstantially transparent non-metallic layers disposed at said rearwardsurface of said substrate, each of said substantially transparentnon-metallic layers and said substantially reflective metallic layerhaving a selected refractive index and a selected physical thicknesssuch that said mirror element is selectively spectrally tuned tosubstantially transmit at least one preselected spectral band of radiantenergy therethrough while substantially reflecting other radiant energy,wherein said at least one preselected spectral band comprises apreselected band of near infrared radiant energy; a radiant energyemitting element at or near said rearward surface of said substrate,said radiant energy emitting element being operable to emit radiantenergy towards said rearward surface and through said mirror element,said radiant energy emitting element being operable to emit nearinfrared radiant energy with a peak intensity within said preselectedspectral band of near infrared radiant energy; and an imaging sensor ator near said rearward surface, said imaging sensor being sensitive tonear infrared radiant energy in the range of approximately 750 nm toapproximately 1100 nm.
 38. A mirror assembly for a vehicle, said mirrorassembly comprising: a mirror element comprising a substrate having aforward surface facing towards a viewer of the mirror assembly and arearward surface facing away from a viewer of the mirror assembly, saidmirror element comprising at least one substantially reflective metalliclayer sandwiched between a respective pair of substantially transparentnon-metallic layers disposed at said rearward surface of said substrate,each of said substantially transparent non-metallic layers and saidsubstantially reflective metallic layer having a selected refractiveindex and a selected physical thickness such that said mirror element isselectively spectrally tuned to substantially transmit at least onepreselected spectral band of radiant energy therethrough whilesubstantially reflecting other radiant energy; and a radiant energyemitting element at or near said rearward surface of said substrate,said radiant energy emitting element being operable to emit radiantenergy towards said rearward surface and through said mirror element,said radiant energy emitting element being operable to emit radiantenergy with a peak intensity within said at least one preselectedspectral band, wherein said at least one preselected spectral bandcomprises first and second preselected bands of radiant energy, saidradiant energy emitting element comprises first and second radiantenergy emitting elements, said first radiant energy emitting elementbeing operable to emit radiant energy with a peak intensity within saidfirst preselected spectral band of radiant energy and said secondradiant energy emitting element being operable to emit radiant energywith a peak intensity within said second preselected spectral band ofradiant energy.
 39. The mirror assembly of claim 38, wherein said firstand second preselected bands of radiant energy comprise first and secondpreselected bands of visible light, said first band being a differentband than said second band.
 40. The mirror assembly of claim 38, whereinsaid first preselected band of radiant energy comprises a band of nearinfrared radiant energy and said second preselected band of radiantenergy comprises a band of visible light.
 41. A mirror assembly for avehicle, said mirror assembly comprising: a mirror element comprising asubstrate having a forward surface facing towards a viewer of the mirrorassembly and a rearward surface facing away from a viewer of the mirrorassembly, wherein said mirror element comprises at least twosubstantially reflective metallic layers, each of said at least twosubstantially reflective metallic conductive layers being sandwichedbetween a respective pair of substantially transparent non-metalliclayers disposed at said rearward surface of said substrate, each of saidsubstantially transparent non-metallic layers and said substantiallyreflective metallic layer having a selected refractive index and aselected physical thickness such that said mirror element is selectivelyspectrally tuned to substantially transmit at least one preselectedspectral band of radiant energy therethrough while substantiallyreflecting other radiant energy; and a radiant energy emitting elementat or near said rearward surface of said substrate, said radiant energyemitting element being operable to emit radiant energy towards saidrearward surface and through said mirror element, said radiant energyemitting element being operable to emit radiant energy with a peakintensity within said at least one preselected spectral band.
 42. Themirror assembly of claim 41, wherein said at least one preselectedspectral band comprises a preselected band of visible light, saidradiant energy emitting element being operable to emit visible radiantenergy with a peak intensity within said preselected spectral band ofvisible light.
 43. The mirror assembly of claim 42, wherein said radiantenergy emitting element comprises a display on demand element.
 44. Themirror assembly of claim 41, wherein said at least one preselectedspectral band comprises a preselected band of near infrared radiantenergy, said radiant energy emitting element being operable to emit nearinfrared radiant energy with a peak intensity within said preselectedspectral band of near infrared radiant energy.
 45. A mirror assembly fora vehicle, said mirror assembly comprising: a mirror element comprisinga substrate having a forward surface facing towards a viewer of themirror assembly and a rearward surface facing away from a viewer of themirror assembly, said mirror element comprising at least onesubstantially reflective metallic layer sandwiched between a respectivepair of substantially transparent non-metallic layers disposed at saidrearward surface of said substrate, each of said substantiallytransparent non-metallic layers and said substantially reflectivemetallic layer having a selected refractive index and a selectedphysical thickness such that said mirror element is selectivelyspectrally tuned to substantially transmit at least one preselectedspectral band of radiant energy therethrough while substantiallyreflecting other radiant energy; a radiant energy emitting element at ornear said rearward surface of said substrate, said radiant energyemitting element being operable to emit radiant energy towards saidrearward surface and through said mirror element, said radiant energyemitting element being operable to emit radiant energy with a peakintensity within said at least one preselected spectral band; and ananti-reflective stack of layers at said rearward surface, saidanti-reflective stack being spectrally tuned to minimize reflectance ofradiant energy at said preselected spectral band.
 46. A mirror assemblyfor a vehicle, said mirror assembly comprising: a mirror elementcomprising a substrate having a forward surface facing towards a viewerof the mirror assembly and a rearward surface facing away from a viewerof the mirror assembly, wherein said substrate comprises a prismaticsubstrate, said mirror element comprising at least one substantiallyreflective metallic layer sandwiched between a respective pair ofsubstantially transparent non-metallic layers disposed at said rearwardsurface of said substrate, each of said substantially transparentnon-metallic layers and said substantially reflective metallic layerhaving a selected refractive index and a selected physical thicknesssuch that said mirror element is selectively spectrally tuned tosubstantially transmit at least one preselected spectral band of radiantenergy therethrough while substantially reflecting other radiant energy;and a radiant energy emitting element at or near said rearward surfaceof said substrate, said radiant energy emitting element being operableto emit radiant energy towards said rearward surface and through saidmirror element, said radiant energy emitting element being operable toemit radiant energy with a peak intensity within said at least onepreselected spectral band.